feat(创建编辑): 完善图片适应、裁剪恢复和字距设置，统一工具栏对齐

assets/webui/index.html

@@ -101,9 +101,17 @@
 					<option value="horizontal">水平</option>
 					<option value="vertical">垂直</option>
 				</select>
+				<span>变换</span>
+			</div>
+			<div class="editor-group editor-image">
+				<select id="imageFit" aria-label="图片适应方式" disabled>
+					<option value="" hidden>缩放</option>
+					<option value="contain">适应</option>
+					<option value="cover">填充</option>
+				</select>
 				<button id="cropImageButton" class="button" type="button" aria-label="裁剪图片" aria-pressed="false" disabled>裁剪</button>
 				<button id="resetCropButton" class="button" type="button" aria-label="还原图片" disabled>还原</button>
-				<span>变换</span>
+				<span>图片</span>
 			</div>
 			<div class="editor-group">
 				<div class="text-font"><select id="textFont" aria-label="字体" title="字体" disabled></select><button id="textFontAdd" class="icon-button" type="button" title="添加字体" aria-label="添加字体">+</button></div>
@@ -118,8 +126,9 @@
 					<option value="right">右齐</option>
 					<option value="justify">两端</option>
 				</select>
-				<button id="textWrap" class="button" type="button" aria-label="自动折行" aria-pressed="false" disabled>折行</button>
 				<label class="editor-field"><span>行距</span><span class="editor-number"><input id="textLineHeight" type="number" min="0" step="any" placeholder="自动" aria-label="行距" title="行距，0为自动" disabled><span>pt</span></span></label>
+				<button id="textWrap" class="button" type="button" aria-label="自动折行" aria-pressed="false" disabled>折行</button>
+				<label class="editor-field"><span>字距</span><span class="editor-number"><input id="textSpacing" type="number" step="any" placeholder="0" aria-label="字距" title="字距" disabled><span>pt</span></span></label>
 				<span>段落</span>
 			</div>
 			<div class="editor-group">
@@ -201,6 +210,10 @@
 					<label for="insertImage">图片</label>
 					<input id="insertImage" type="file" accept=".png,.jpg,.jpeg,image/png,image/jpeg" required autofocus>
 				</div>
+				<div id="insertFitRow" class="form-row" hidden>
+					<label for="insertFit">缩放</label>
+					<select id="insertFit"><option value="contain">适应</option><option value="cover">填充</option></select>
+				</div>
 				<div class="form-actions">
 					<div id="insertStatus" class="form-status" role="status"></div>
 					<button id="insertCancel" class="button" type="button">取消</button>

assets/webui/ofdgo.css

@@ -113,12 +113,24 @@ a:focus-visible {
 
 .editor-file,
 .editor-paragraph,
-.editor-transform,
+.editor-image,
 .editor-group:has(#textFont),
 .editor-group:has(#shapeFill) {
 	grid-template-columns: repeat(2, max-content);
 }
 
+.editor-transform {
+	grid-template-columns: max-content;
+}
+
+.editor-image > select {
+	grid-column: 1 / -1;
+}
+
+.editor-paragraph > .editor-field {
+	grid-column: auto;
+}
+
 .editor-objects {
 	grid-template-columns: repeat(4, max-content);
 }
@@ -178,8 +190,8 @@ a:focus-visible {
 }
 
 .editor-paragraph {
-	width: 172px;
+	width: 218px;
-	grid-template-columns: repeat(2, minmax(0, 1fr));
+	grid-template-columns: 54px minmax(0, 1fr);
 }
 
 .editor-file #saveButton {
@@ -196,6 +208,14 @@ a:focus-visible {
 	min-width: 0;
 }
 
+#textColor {
+	width: 100%;
+}
+
+.shape-paint {
+	justify-content: space-between;
+}
+
 .shape-paint,
 .shape-paint label {
 	display: flex;

assets/webui/ofdgo.js

@@ -39,7 +39,7 @@ const state = {
 	insertObject: null,
 	textFonts: [],
 	textFontID: null,
-	textDefaults: { type: "TextObject", size: 12 * 25.4 / 72, color: "#000000", wrap: true, align: "left", paragraphHeight: 0 },
+	textDefaults: { type: "TextObject", size: 12 * 25.4 / 72, color: "#000000", wrap: true, align: "left", paragraphHeight: 0, letterSpacing: 0 },
 	ofdBytes: null,
 	fileName: "ofdgo.ofd",
 	openSeq: 0,
@@ -95,12 +95,14 @@ const el = {
 	objectDistribute: document.querySelector("#objectDistribute"),
 	objectRotate: document.querySelector("#objectRotate"),
 	objectFlip: document.querySelector("#objectFlip"),
+	imageFit: document.querySelector("#imageFit"),
 	cropImageButton: document.querySelector("#cropImageButton"),
 	resetCropButton: document.querySelector("#resetCropButton"),
 	multiSelectButton: document.querySelector("#multiSelectButton"),
 	textAlign: document.querySelector("#textAlign"),
 	textWrap: document.querySelector("#textWrap"),
 	textLineHeight: document.querySelector("#textLineHeight"),
+	textSpacing: document.querySelector("#textSpacing"),
 	textFont: document.querySelector("#textFont"),
 	textFontAdd: document.querySelector("#textFontAdd"),
 	textSize: document.querySelector("#textSize"),
@@ -142,6 +144,8 @@ const el = {
 	insertPanel: document.querySelector("#insertPanel"),
 	insertForm: document.querySelector("#insertForm"),
 	insertImage: document.querySelector("#insertImage"),
+	insertFitRow: document.querySelector("#insertFitRow"),
+	insertFit: document.querySelector("#insertFit"),
 	insertStatus: document.querySelector("#insertStatus"),
 	insertCancel: document.querySelector("#insertCancel"),
 	insertSubmit: document.querySelector("#insertSubmit"),
@@ -244,7 +248,7 @@ const canvasEditor = new CanvasEditor(el.viewerPanel, {
 	onTransform: (item, change) => changeDocument(item.items ? "ofdgoTransformObjects" : "ofdgoTransformObject", item,
 		change.x + item.x * (1 - change.scale), change.y + item.y * (1 - change.scale), change.scale),
 	onReshape: (item, box) => changeDocument("ofdgoReshapeObject", item, box.x, box.y, box.width, box.height),
-	onTextWidth: (item, box) => changeDocument("ofdgoLayoutText", item, box.x - item.x, box.width, true, item.align || "", item.paragraphHeight || 0),
+	onTextWidth: (item, box) => changeDocument("ofdgoLayoutText", item, box.x - item.x, box.width, true, item.align || "", item.paragraphHeight || 0, item.letterSpacing || 0),
 	onCrop: (item, box) => changeDocument("ofdgoCropImage", item, box.x, box.y, box.width, box.height),
 	onCropChange: () => {
 		updatePendingChanges();
@@ -259,7 +263,7 @@ const canvasEditor = new CanvasEditor(el.viewerPanel, {
 		box.x, box.y, box.width, box.height, style.fill, style.fillColor, style.stroke, style.strokeColor, style.lineWidth),
 	onDrawText: beginCanvasText,
 	onCommitText: (item, value, fontData) => item.draft
-		? changeDocument("ofdgoInsertText", null, item.index, value, fontData || item.fontData, item.x, item.y, item.size, item.color, item.width, item.wrap, item.align, item.paragraphHeight)
+		? changeDocument("ofdgoInsertText", null, item.index, value, fontData || item.fontData, item.x, item.y, item.size, item.color, item.width, item.wrap, item.align, item.paragraphHeight, item.letterSpacing)
 		: changeDocument("ofdgoUpdateText", item, value, fontData || null, item.size, null),
 	onTextChange: () => {
 		const editing = canvasEditor.input;
@@ -271,7 +275,6 @@ const canvasEditor = new CanvasEditor(el.viewerPanel, {
 	},
 });
 
-// updatePendingChanges 将未提交的文字和裁剪计入修改状态，不生成历史记录。
 function updatePendingChanges() {
 	const editing = canvasEditor.input;
 	setDirty(state.editing && (state.editorInfo?.revision !== state.savedRevision
@@ -282,7 +285,6 @@ el.editorTools.addEventListener("pointerdown", (event) => {
 	if (canvasEditor.input && event.target.closest("button")) event.preventDefault();
 });
 
-// editorClick 提交画布中的文字和裁剪后，再执行工具栏操作。
 function editorClick(button, action) {
 	button.addEventListener("click", async () => {
 		if (canvasEditor.input && !await canvasEditor.commitText()) return;
@@ -323,9 +325,10 @@ el.textColor.addEventListener("change", () => changeTextStyle(true));
 editorClick(el.textWrap, () => changeParagraph(!currentTextStyle().wrap));
 el.textAlign.addEventListener("change", () => changeParagraph());
 el.textLineHeight.addEventListener("change", () => changeParagraph());
+el.textSpacing.addEventListener("change", () => changeParagraph());
 el.textFont.addEventListener("change", changeTextFont);
 el.shapeWidth.addEventListener("focus", () => { el.shapeWidth.defaultValue = el.shapeWidth.value; });
-for (const input of [el.textSize, el.shapeWidth, el.textLineHeight]) {
+for (const input of [el.textSize, el.shapeWidth, el.textLineHeight, el.textSpacing]) {
 	input.addEventListener("keydown", (event) => {
 		if (event.isComposing) return;
 		if (event.key === "Enter" || event.key === "Escape") {
@@ -387,7 +390,12 @@ el.cropImageButton.addEventListener("click", () => {
 	if (document.body.hasAttribute("aria-busy")) return;
 	if (canvasEditor.crop) return canvasEditor.commitCrop();
 	const item = canvasEditor.selected;
-	if (item?.type === "ImageObject") canvasEditor.startCrop(item);
+	if (item?.type === "ImageObject") return startImageCrop(item);
+});
+el.imageFit.addEventListener("change", () => {
+	const mode = el.imageFit.value, item = canvasEditor.selected;
+	el.imageFit.value = "";
+	if (mode && item?.type === "ImageObject" && !canvasEditor.crop) return changeDocument("ofdgoFitImage", item, mode);
 });
 el.resetCropButton.addEventListener("click", () => {
 	if (document.body.hasAttribute("aria-busy")) return;
@@ -788,12 +796,46 @@ async function editCanvasObject(item) {
 	}
 }
 
+async function startImageCrop(item) {
+	const openSeq = state.openSeq;
+	const urls = [];
+	let mounted = false;
+	setBusy(true);
+	try {
+		const page = await callWASM("ofdgoPreviewImage", item.index, item.id);
+		if (openSeq !== state.openSeq || !item.surface.isConnected) return;
+		const images = new Map(state.svgImages);
+		for (const image of page.images) {
+			if (images.has(image.name)) continue;
+			const url = URL.createObjectURL(new Blob([image.bytes], { type: image.mime }));
+			urls.push(url);
+			images.set(image.name, { url });
+		}
+		await Promise.all(urls.map(url => {
+			const image = new Image();
+			image.src = url;
+			return image.decode();
+		}));
+		if (openSeq !== state.openSeq || canvasEditor.selected !== item) return;
+		const svg = parseSVG(page.svg, `crop${openSeq}-${item.id}`, images);
+		svg.classList.add("ofd-svg");
+		canvasEditor.startCrop(item, { svg, urls });
+		mounted = true;
+	} catch (err) {
+		if (openSeq === state.openSeq) showError(err, false);
+	} finally {
+		if (!mounted) urls.forEach(url => URL.revokeObjectURL(url));
+		if (openSeq === state.openSeq) setBusy(false);
+	}
+}
+
 function openInsertPanel(item = null) {
 	if (!state.editing || document.body.hasAttribute("aria-busy")) {
 		return;
 	}
 	el.insertForm.reset();
 	state.insertObject = item;
+	el.insertFitRow.hidden = !item;
 	el.insertPanel.setAttribute("aria-label", item ? "替换图片" : "添加图片");
 	el.insertSubmit.textContent = item ? "替换" : "添加";
 	el.insertStatus.textContent = "";
@@ -801,12 +843,10 @@ function openInsertPanel(item = null) {
 	el.insertImage.focus();
 }
 
-// currentTextStyle 获取所选文字样式，未选中文字时使用新文字的默认样式。
 function currentTextStyle() {
 	return canvasEditor.selected?.type === "TextObject" ? canvasEditor.selected : state.textDefaults;
 }
 
-// toggleTextTool 切换画布文字工具，不提前创建空文字对象。
 async function toggleTextTool() {
 	if (!state.editing || document.body.hasAttribute("aria-busy")) return;
 	if (canvasEditor.tool === "text") {
@@ -821,7 +861,7 @@ async function toggleTextTool() {
 	if (openSeq !== state.openSeq) return;
 	const style = currentTextStyle();
 	state.textDefaults = { type: "TextObject", size: style.size, color: style.color, wrap: style.wrap,
-		align: style.align || "left", paragraphHeight: style.paragraphHeight || 0,
+		align: style.align || "left", paragraphHeight: style.paragraphHeight || 0, letterSpacing: style.letterSpacing || 0,
 		fontChoice: state.textFonts[Number(el.textFont.value)] || state.textDefaults.fontChoice };
 	state.selectObjects = true;
 	setPan(false);
@@ -829,7 +869,6 @@ async function toggleTextTool() {
 	el.viewerPanel.focus({ preventScroll: true });
 }
 
-// beginCanvasText 加载所选本地字体，并在画布上创建待提交的文字输入框。
 async function beginCanvasText(index, box, surface, page) {
 	const font = state.textDefaults.fontChoice || state.textFonts[Number(el.textFont.value)];
 	if (!font) {
@@ -889,7 +928,6 @@ function updateTextFonts(item, refresh = false) {
 	}
 }
 
-// changeTextFont 更换字体时保留尚未提交的文字。
 async function changeTextFont() {
 	const item = canvasEditor.selected;
 	const font = state.textFonts[Number(el.textFont.value)];
@@ -943,7 +981,7 @@ async function insertObject(event) {
 			return;
 		}
 		const doc = item
-			? await callWASM("ofdgoReplaceImage", item.index, item.id, data)
+			? await callWASM("ofdgoReplaceImage", item.index, item.id, data, el.insertFit.value)
 			: await callWASM("ofdgoInsertImage", index, data, x, y, page.width - x * 2);
 		if (openSeq !== state.openSeq) {
 			return;
@@ -981,7 +1019,6 @@ function textPoints(size) {
 	return Number((size * 72 / 25.4).toFixed(2));
 }
 
-// changeParagraph 仅提交变更的段落选项，具体排版由库完成。
 async function changeParagraph(wrap = currentTextStyle().wrap) {
 	const item = currentTextStyle();
 	if (document.body.hasAttribute("aria-busy") || item.draft) return;
@@ -991,12 +1028,18 @@ async function changeParagraph(wrap = currentTextStyle().wrap) {
 	}
 	const points = Number(el.textLineHeight.value);
 	const height = points === textPoints(item.paragraphHeight || 0) ? item.paragraphHeight || 0 : points * 25.4 / 72;
-	if (item === state.textDefaults) {
+	if (!el.textSpacing.checkValidity()) {
-		Object.assign(item, { wrap: Boolean(wrap), align: el.textAlign.value, paragraphHeight: height });
 		updateObjectControls(canvasEditor.selected, true);
 		return;
 	}
-	await changeDocument("ofdgoLayoutText", item, null, null, Boolean(wrap), el.textAlign.value, height);
+	const spacingPoints = Number(el.textSpacing.value);
+	const spacing = spacingPoints === textPoints(item.letterSpacing || 0) ? item.letterSpacing || 0 : spacingPoints * 25.4 / 72;
+	if (item === state.textDefaults) {
+		Object.assign(item, { wrap: Boolean(wrap), align: el.textAlign.value, paragraphHeight: height, letterSpacing: spacing });
+		updateObjectControls(canvasEditor.selected, true);
+		return;
+	}
+	await changeDocument("ofdgoLayoutText", item, null, null, Boolean(wrap), el.textAlign.value, height, spacing);
 	updateObjectControls(canvasEditor.selected, true);
 }
 
@@ -2984,9 +3027,9 @@ function layoutPageShell(shell, page) {
 	}
 }
 
-function parseSVG(svgText, prefix = "") {
+function parseSVG(svgText, prefix = "", images = state.svgImages) {
 	const template = document.createElement("template");
-	template.innerHTML = svgText.replace(/xlink:href="(ofdgo-image-[a-f0-9]{64})"/g, (_, name) => `xlink:href="${state.svgImages.get(name).url}"`);
+	template.innerHTML = svgText.replace(/xlink:href="(ofdgo-image-[a-f0-9]{64})"/g, (_, name) => `xlink:href="${images.get(name).url}"`);
 	const svg = document.adoptNode(template.content.firstElementChild);
 	prefixSVGIds(svg, prefix);
 	return svg;
@@ -4206,6 +4249,7 @@ function updateObjectControls(item, reset = false) {
 	el.objectAlign.disabled = disabled || cropping;
 	el.objectRotate.disabled = el.objectFlip.disabled = disabled || cropping;
 	el.cropImageButton.disabled = disabled || item.type !== "ImageObject";
+	el.imageFit.disabled = el.cropImageButton.disabled || cropping;
 	el.cropImageButton.textContent = cropping ? "完成" : "裁剪";
 	el.cropImageButton.setAttribute("aria-label", cropping ? "完成裁剪" : "裁剪图片");
 	el.cropImageButton.setAttribute("aria-pressed", String(cropping));
@@ -4219,12 +4263,15 @@ function updateObjectControls(item, reset = false) {
 	el.textFont.disabled = !state.editing || !state.ready || state.exporting || Boolean(item?.items);
 	el.textSize.disabled = el.textColor.disabled = el.textFont.disabled || Boolean(item?.draft);
 	el.textFontAdd.disabled = !state.editing || !state.ready || state.exporting;
-	el.textAlign.disabled = el.textWrap.disabled = el.textLineHeight.disabled = el.textSize.disabled;
+	el.textAlign.disabled = el.textWrap.disabled = el.textLineHeight.disabled = el.textSpacing.disabled = el.textSize.disabled;
 	el.textAlign.value = text.align || "left";
 	el.textWrap.setAttribute("aria-pressed", String(Boolean(text.wrap)));
 	if (reset || document.activeElement !== el.textLineHeight) {
 		el.textLineHeight.value = text.paragraphHeight ? String(textPoints(text.paragraphHeight)) : "";
 	}
+	if (reset || document.activeElement !== el.textSpacing) {
+		el.textSpacing.value = text.letterSpacing ? String(textPoints(text.letterSpacing)) : "";
+	}
 	updateTextFonts(item);
 	if (reset || el.textSize.disabled || document.activeElement !== el.textSize) {
 		el.textSize.value = document.activeElement === el.textSize ? textPoints(text.size) : Math.round(textPoints(text.size));

assets/webui/ofdgo_edit.js

@@ -21,14 +21,12 @@ export function objectTransform(box, dx, dy, corner = "") {
 	return { x: left ? box.width * (1 - scale) : 0, y: top ? box.height * (1 - scale) : 0, scale };
 }
 
-// selectionBounds 计算同页对象的联合边界，不改变对象位置。
 export function selectionBounds(items) {
 	const x = Math.min(...items.map(item => item.x)), y = Math.min(...items.map(item => item.y));
 	return { x, y, width: Math.max(...items.map(item => item.x + item.width)) - x,
 		height: Math.max(...items.map(item => item.y + item.height)) - y };
 }
 
-// alignmentGuides 查找最近的边缘或中心辅助线，不改变对象坐标。
 function alignmentGuides(box, targets, tolerance) {
 	const lines = [];
 	for (const [axis, size, cross, span] of [["x", "width", "y", "height"], ["y", "height", "x", "width"]]) {
@@ -51,7 +49,6 @@ function alignmentGuides(box, targets, tolerance) {
 	return lines.join("");
 }
 
-// transformedBox 将本地矩形映射到页面，用于变换后的文字框预览。
 function transformedBox(box, matrix) {
 	const [a, b, c, d, e, f] = matrix;
 	const points = [[box.x, box.y], [box.x + box.width, box.y], [box.x, box.y + box.height], [box.x + box.width, box.y + box.height]]
@@ -60,7 +57,6 @@ function transformedBox(box, matrix) {
 	return { x, y, width: Math.max(...points.map(p => p[0])) - x, height: Math.max(...points.map(p => p[1])) - y };
 }
 
-// cropBox 将保留区域限制在当前图片范围内，不改变图片比例。
 function cropBox(box, bounds, dx, dy, corner) {
 	if (!corner) return { ...box, x: Math.max(bounds.x, Math.min(box.x + dx, bounds.x + bounds.width - box.width)),
 		y: Math.max(bounds.y, Math.min(box.y + dy, bounds.y + bounds.height - box.height)) };
@@ -70,7 +66,6 @@ function cropBox(box, bounds, dx, dy, corner) {
 		height: Math.min(bounds.y + bounds.height, next.y + next.height) - y };
 }
 
-// constrainedPoint 按修饰键约束图形端点，允许超出页面边界。
 export function constrainedPoint(from, to, shape, shift) {
 	let dx = to.x - from.x, dy = to.y - from.y;
 	if (shift && shape === "line") {
@@ -87,7 +82,6 @@ export function constrainedPoint(from, to, shape, shift) {
 	return { x: from.x + dx, y: from.y + dy };
 }
 
-// reshapeBox 移动线段端点或调整基本图形范围，不缩放描边。
 export function reshapeBox(item, dx, dy, handle, shift) {
 	const box = item.geometry;
 	if (!dx && !dy && !shift) return { ...box };
@@ -112,7 +106,6 @@ export function reshapeBox(item, dx, dy, handle, shift) {
 	return { x, y, width: right - x, height: bottom - y };
 }
 
-// paintShape 使用统一的页面坐标绘制图形及端点调整预览。
 function paintShape(node, shape, box) {
 	const { x, y, width, height } = box;
 	const attributes = shape === "line" ? { x1: x, y1: y, x2: x + width, y2: y + height }
@@ -172,7 +165,7 @@ export class CanvasEditor {
 
 	mount(index, page, surface) {
 		const crop = this.crop?.item.index === index ? this.crop : null;
-		if (crop) this.closeCrop();
+		if (crop) this.closeCrop(true);
 		const pending = this.pendingSelection?.index === index;
 		const selected = pending ? this.pendingSelection.ids || page.objects.slice(-1).map(item => item.id)
 			: this.items().filter(item => item.index === index).map(item => item.id);
@@ -212,9 +205,11 @@ export class CanvasEditor {
 		if (pending) this.pendingSelection = null;
 		if (crop && selection.length === 1 && selection[0].id === crop.item.id
 			&& ["x", "y", "width", "height"].every(key => selection[0][key] === crop.item[key])) {
-			this.startCrop(selection[0]);
+			this.startCrop(selection[0], crop.pagePreview);
 			this.crop.box = { ...crop.box };
 			this.paintCrop();
+		} else if (crop) {
+			crop.pagePreview.urls.forEach(url => URL.revokeObjectURL(url));
 		}
 	}
 
@@ -247,7 +242,6 @@ export class CanvasEditor {
 		}
 	}
 
-	// placeShape 按图形几何范围放置手柄，不包含边界留量。
 	placeShape(item, box) {
 		const x = Math.min(box.x, box.x + box.width), y = Math.min(box.y, box.y + box.height);
 		Object.assign(item.node.style, {
@@ -263,12 +257,10 @@ export class CanvasEditor {
 		}
 	}
 
-	// items 获取选中的真实对象，临时多选框不作为文档对象。
 	items() {
 		return this.selected?.items || (this.selected ? [this.selected] : []);
 	}
 
-	// setSelection 更新同页对象选区，并同步工具栏。
 	setSelection(items) {
 		if (this.crop && (items.length !== 1 || items[0] !== this.crop.item)) this.closeCrop();
 		if (this.selected?.items) this.selected.node.remove();
@@ -391,7 +383,7 @@ export class CanvasEditor {
 		if (drag.crop) {
 			const from = pagePoint(drag.clientX, drag.clientY, drag.rect, drag.page, drag.rotation);
 			const to = pagePoint(event.clientX, event.clientY, drag.rect, drag.page, drag.rotation);
-			this.crop.box = cropBox(drag.box, this.crop.item, to.x - from.x, to.y - from.y, drag.corner);
+			this.crop.box = cropBox(drag.box, this.crop.item.imageBounds, to.x - from.x, to.y - from.y, drag.corner);
 			this.paintCrop();
 			return;
 		}
@@ -434,7 +426,6 @@ export class CanvasEditor {
 		if (!drag.corner) this.showGuides(drag);
 	}
 
-	// showGuides 在页面缩放和旋转时保持辅助线的屏幕判定距离一致。
 	showGuides(drag) {
 		const { item, rect, rotation, change } = drag;
 		const path = alignmentGuides({ ...item, x: item.x + change.x, y: item.y + change.y }, drag.targets, {
@@ -528,7 +519,6 @@ export class CanvasEditor {
 		}
 	}
 
-	// startMarquee 在页面坐标中开始框选，统一处理缩放和旋转。
 	startMarquee(event, additive) {
 		const surface = event.target.closest(".page-surface"), page = this.pages.get(surface);
 		if (!page) {
@@ -546,7 +536,6 @@ export class CanvasEditor {
 		this.viewer.setPointerCapture(event.pointerId);
 	}
 
-	// moveMarquee 选中与框选区域相交的对象，支持追加到已有选区。
 	moveMarquee(event, drag) {
 		const from = pagePoint(drag.clientX, drag.clientY, drag.rect, drag.page, drag.rotation);
 		const to = pagePoint(event.clientX, event.clientY, drag.rect, drag.page, drag.rotation);
@@ -583,7 +572,6 @@ export class CanvasEditor {
 		this.viewer.setPointerCapture(event.pointerId);
 	}
 
-	// nearestSurface 为页面外开始的手势确定一个已加载页面，拖动期间不切换页面。
 	nearestSurface(event) {
 		let nearest = null, distance = Infinity;
 		for (const surface of this.viewer.querySelectorAll(".page-surface")) {
@@ -599,7 +587,6 @@ export class CanvasEditor {
 		return nearest;
 	}
 
-	// createPreview 创建临时SVG预览层，拖动期间不重新渲染页面。
 	createPreview(surface, page, shape, style) {
 		const preview = document.createElementNS("http://www.w3.org/2000/svg", "svg");
 		preview.classList.add("edit-preview");
@@ -631,7 +618,6 @@ export class CanvasEditor {
 			? { x: from.x, y: from.y, width: to.x - from.x, height: to.y - from.y } : { x, y, width, height });
 	}
 
-	// modifierChange 在指针静止时响应Shift变化并刷新预览。
 	modifierChange(event) {
 		const pointer = this.drag?.pointer;
 		if (event.key === "Shift" && pointer) {
@@ -707,6 +693,7 @@ export class CanvasEditor {
 			fontFamily: `"${face.family}"`, fontSize: `${item.size * PX_PER_MM}px`,
 			lineHeight: item.paragraphHeight || item.lineHeight ? `${(item.paragraphHeight || item.lineHeight) * PX_PER_MM}px` : "normal", color: item.color,
 			textAlign: item.align || "left",
+			letterSpacing: `${(item.letterSpacing || 0) * PX_PER_MM}px`,
 		});
 		if (item.textFrame) {
 			const { width, height, matrix: [a, b, c, d, e, f] } = item.textFrame;
@@ -741,14 +728,12 @@ export class CanvasEditor {
 		if (!item.draft) input.select();
 	}
 
-	// resizeText 按当前字体和内容调整输入框，不修改文档中的几何范围。
 	resizeText() {
 		const { input } = this.input;
 		input.style.height = "0px";
 		input.style.height = `${input.scrollHeight + 2}px`;
 	}
 
-	// setTextFont 暂存输入框字体，后续与文字内容一起提交。
 	setTextFont(face, data) {
 		const editing = this.input;
 		document.fonts.add(face);
@@ -794,12 +779,16 @@ export class CanvasEditor {
 		}
 	}
 
-	// startCrop 开始调整图片保留区域，确认前不修改文档。
+	startCrop(item, pagePreview) {
-	startCrop(item) {
 		this.cancel();
 		this.closeCrop();
 		this.setTool("");
-		const box = { x: item.x, y: item.y, width: item.width, height: item.height };
+		const bounds = item.imageBounds;
+		const x = Math.max(item.x, bounds.x), y = Math.max(item.y, bounds.y);
+		const box = { x, y, width: Math.min(item.x + item.width, bounds.x + bounds.width) - x,
+			height: Math.min(item.y + item.height, bounds.y + bounds.height) - y };
+		const original = item.surface.querySelector(".ofd-svg");
+		original.replaceWith(pagePreview.svg);
 		const { preview, node: mask } = this.createPreview(item.surface, item.page, "path", { fill: true, fillColor: "rgba(255,255,255,0.72)" });
 		mask.setAttribute("fill-rule", "evenodd");
 		const node = document.createElement("div");
@@ -812,26 +801,23 @@ export class CanvasEditor {
 		}
 		item.surface.append(node);
 		item.surface.classList.add("cropping");
-		this.crop = { item, box, node, mask, preview };
+		this.crop = { item, box, initialBox: { ...box }, node, mask, preview, original, pagePreview };
 		this.paintCrop();
 		this.viewer.focus({ preventScroll: true });
 	}
 
-	// paintCrop 更新遮罩及手柄，不重新渲染或复制图片数据。
 	paintCrop() {
 		const { item, box, node, mask } = this.crop;
 		const rectangle = b => `M${b.x} ${b.y}h${b.width}v${b.height}h${-b.width}Z`;
-		mask.setAttribute("d", rectangle(item) + rectangle(box));
+		mask.setAttribute("d", rectangle(item.imageBounds) + rectangle(box));
 		Object.assign(node.style, { left: `${box.x * PX_PER_MM}px`, top: `${box.y * PX_PER_MM}px`, width: `${box.width * PX_PER_MM}px`, height: `${box.height * PX_PER_MM}px` });
 		this.options.onCropChange();
 	}
 
-	// cropChanged 判断裁剪范围是否有待提交的变更。
 	cropChanged() {
-		return Boolean(this.crop && ["x", "y", "width", "height"].some(key => this.crop.box[key] !== this.crop.item[key]));
+		return Boolean(this.crop && ["x", "y", "width", "height"].some(key => this.crop.box[key] !== this.crop.initialBox[key]));
 	}
 
-	// commitCrop 将裁剪作为一次可撤销操作提交，失败时保留预览。
 	async commitCrop() {
 		if (!this.crop) return true;
 		if (this.options.busy()) return false;
@@ -845,14 +831,15 @@ export class CanvasEditor {
 		return Boolean(saved);
 	}
 
-	// closeCrop 移除临时裁剪区域，不修改文档内容。
+	closeCrop(keepPreview = false) {
-	closeCrop() {
 		if (!this.crop) return;
 		if (this.drag?.crop) this.cancel();
 		const crop = this.crop;
 		this.crop = null;
 		crop.node.remove();
 		crop.preview.remove();
+		crop.pagePreview.svg.replaceWith(crop.original);
+		if (!keepPreview) crop.pagePreview.urls.forEach(url => URL.revokeObjectURL(url));
 		crop.item.surface.classList.remove("cropping");
 		this.options.onCropChange();
 	}

internal/webui/wasm.go

@@ -119,6 +119,8 @@ func RunWASM() {
 	registerCallback("ofdgoRotateObjects", rotateObjects)
 	registerCallback("ofdgoFlipObjects", flipObjects)
 	registerCallback("ofdgoCropImage", cropImage)
+	registerCallback("ofdgoFitImage", fitImage)
+	registerCallback("ofdgoPreviewImage", previewImage)
 	registerCallback("ofdgoDeleteObject", deleteObject)
 	registerCallback("ofdgoUndo", func([]js.Value) (any, error) { return restoreEditor(false) })
 	registerCallback("ofdgoRedo", func([]js.Value) (any, error) { return restoreEditor(true) })
@@ -318,10 +320,6 @@ func renderPage(args []js.Value) (any, error) {
 	for i, font := range page.Fonts {
 		fonts[i] = map[string]any{"name": font.Name, "weight": font.Weight, "style": font.Style}
 	}
-	images := make([]any, len(page.Images))
-	for i, image := range page.Images {
-		images[i] = map[string]any{"name": image.Name, "mime": image.MIME, "bytes": bytesToJS(image.Data)}
-	}
 	return successResult(map[string]any{
 		"index":   page.Index,
 		"number":  page.Number,
@@ -331,7 +329,7 @@ func renderPage(args []js.Value) (any, error) {
 		"svg":     page.SVG,
 		"links":   links,
 		"fonts":   fonts,
-		"images":  images,
+		"images":  svgImagesToJS(page.Images),
 		"text":    string(textData),
 		"objects": objects,
 	}), nil
@@ -662,6 +660,7 @@ func editorObjects(index int, text *ofdgo.PageText) ([]any, error) {
 					value, layout := source.TextObject.TextLayout()
 					item["text"], item["font"], item["fontName"], item["size"] = value, object.TextObject.Font, fontNames[object.TextObject.Font], object.TextObject.Size
 					item["wrap"], item["align"], item["paragraphHeight"] = layout.Wrap, layout.Align, layout.LineHeight
+					item["letterSpacing"] = layout.LetterSpacing
 					frame, err := object.TextObject.TextFrame()
 					if err != nil {
 						return nil, err
@@ -724,7 +723,7 @@ func editorFont(args []js.Value) (any, error) {
 }
 
 // replaceImage 替换图片资源并更新预览
-// 入参: args 页码、对象标识和图片数据
+// 入参: args 页码、对象标识、图片数据和适应方式
 // 返回: any 文档信息, error 错误信息
 func replaceImage(args []js.Value) (any, error) {
 	if currentEditor == nil {
@@ -735,7 +734,7 @@ func replaceImage(args []js.Value) (any, error) {
 		return nil, err
 	}
 	revision := currentEditor.Revision()
-	if err := currentEditor.ReplaceImage(args[0].Int(), args[1].String(), data); err != nil {
+	if err := currentEditor.ReplaceImage(args[0].Int(), args[1].String(), data, args[3].String()); err != nil {
 		return nil, err
 	}
 	if currentEditor.Revision() == revision {
@@ -1106,7 +1105,7 @@ func updatePathStyle(args []js.Value) (any, error) {
 }
 
 // insertText 使用选定字体创建文字对象
-// 入参: args 页码、内容、字体数据、横纵坐标、字号、颜色、框宽、折行、对齐和行距
+// 入参: args 页码、内容、字体数据、横纵坐标、字号、颜色、框宽、折行、对齐、行距和字距
 // 返回: any 文档信息, error 错误信息
 func insertText(args []js.Value) (any, error) {
 	if currentEditor == nil {
@@ -1139,7 +1138,7 @@ func insertText(args []js.Value) (any, error) {
 		Boundary: fmt.Sprintf("%g %g %g %g", box.X, box.Y, box.W, box.H),
 		Font:     fontID, Size: args[5].Float(),
 	}}
-	if err := currentEditor.LayoutText(&object.TextObject, args[1].String(), ofdgo.TextLayout{Wrap: args[8].Bool(), Align: args[9].String(), LineHeight: args[10].Float()}); err != nil {
+	if err := currentEditor.LayoutText(&object.TextObject, args[1].String(), ofdgo.TextLayout{Wrap: args[8].Bool(), Align: args[9].String(), LineHeight: args[10].Float(), LetterSpacing: args[11].Float()}); err != nil {
 		return nil, err
 	}
 	if err := setTextColor(&object.TextObject, args[6].String()); err != nil {
@@ -1152,7 +1151,7 @@ func insertText(args []js.Value) (any, error) {
 }
 
 // layoutText 调整文字框和段落排版，保留软换行前的原文。
-// 入参: args 页码、对象标识、本地左侧偏移、宽度、折行、对齐和行距
+// 入参: args 页码、对象标识、本地左侧偏移、宽度、折行、对齐、行距和字距
 // 返回: any 文档信息, error 错误信息
 func layoutText(args []js.Value) (any, error) {
 	if currentEditor == nil {
@@ -1173,7 +1172,7 @@ func layoutText(args []js.Value) (any, error) {
 		}
 	}
 	value, _ := object.TextObject.TextLayout()
-	if err := currentEditor.LayoutText(&object.TextObject, value, ofdgo.TextLayout{Wrap: args[4].Bool(), Align: args[5].String(), LineHeight: args[6].Float()}); err != nil {
+	if err := currentEditor.LayoutText(&object.TextObject, value, ofdgo.TextLayout{Wrap: args[4].Bool(), Align: args[5].String(), LineHeight: args[6].Float(), LetterSpacing: args[7].Float()}); err != nil {
 		return nil, err
 	}
 	revision := currentEditor.Revision()
@@ -1230,6 +1229,59 @@ func cropImage(args []js.Value) (any, error) {
 	})
 }
 
+// fitImage 按原始比例适应或填充图片框。
+// 入参: args 页面索引、对象标识和适应方式
+// 返回: any 文档信息, error 错误信息
+func fitImage(args []js.Value) (any, error) {
+	return changeObjects(func() error {
+		return currentEditor.FitImage(args[0].Int(), args[1].String(), args[2].String())
+	})
+}
+
+// previewImage 在页面副本中显示指定图片的完整内容，不改变正文、历史或缓存。
+// 入参: args 页面索引和图片对象标识
+// 返回: any 页面SVG和分离的图片资源, error 错误信息
+func previewImage(args []js.Value) (any, error) {
+	if currentEditor == nil {
+		return nil, fmt.Errorf("no document is being created")
+	}
+	page, err := currentEditor.Page(args[0].Int())
+	if err != nil {
+		return nil, err
+	}
+	id := args[1].String()
+	found := false
+	for i := range page.Content.Layer {
+		for j := range page.Content.Layer[i].Objects {
+			object := &page.Content.Layer[i].Objects[j]
+			if object.Type == "ImageObject" && object.ImageObject.ID == id {
+				object.ImageObject.Clips = nil
+				found = true
+			}
+		}
+	}
+	if !found {
+		return nil, fmt.Errorf("image object %q not found", id)
+	}
+	var out bytes.Buffer
+	resources, err := currentSession.Renderer.RenderToSVGWithResources(page, &out)
+	if err != nil {
+		return nil, err
+	}
+	return successResult(map[string]any{"svg": out.String(), "images": svgImagesToJS(resources.Images)}), nil
+}
+
+// svgImagesToJS 将图片资源以二进制数组传给前端，不使用base64。
+// 入参: images SVG引用的图片资源
+// 返回: []any 图片标识、类型和数据
+func svgImagesToJS(images []ofdgo.SVGImage) []any {
+	items := make([]any, len(images))
+	for i, image := range images {
+		items[i] = map[string]any{"name": image.Name, "mime": image.MIME, "bytes": bytesToJS(image.Data)}
+	}
+	return items
+}
+
 // transformObjects 统一移动或缩放选区，生成一次撤销记录。
 // 入参: args 页面索引、对象标识数组、横纵位移和正缩放比例
 // 返回: any 文档信息, error 错误信息

ofdgo_editor.go

@@ -40,7 +40,7 @@ type Editor struct {
 	pages        []PageContent
 	resources    []editorResource
 	fonts        map[string]*font.SFNT
-	images       map[string]bool
+	images       map[string]image.Point
 	resourceID   map[editorResourceKey]string
 	maxID        int
 	history      []editorChange
@@ -77,7 +77,7 @@ func NewEditor() *Editor {
 			CreationDate: time.Now().Format("2006-01-02"),
 		},
 		fonts:      make(map[string]*font.SFNT),
-		images:     make(map[string]bool),
+		images:     make(map[string]image.Point),
 		resourceID: make(map[editorResourceKey]string),
 	}
 }
@@ -346,7 +346,7 @@ func (e *Editor) AddImage(data []byte) (string, error) {
 		data:  bytes.Clone(data),
 		image: &MultiMedia{ID: id, Type: "Image", Format: strings.ToUpper(format), MediaFile: name},
 	})
-	e.images[id] = true
+	e.images[id] = image.Pt(config.Width, config.Height)
 	e.resourceID[key] = id
 	return id, nil
 }
@@ -554,7 +554,7 @@ func (e *Editor) prepareObject(id string, object GraphicObject) (GraphicObject,
 		fill, stroke = obj.FillColor, (*FillColor)(obj.StrokeColor)
 	case "ImageObject":
 		obj := &object.ImageObject
-		if !e.images[obj.ResourceID] || (obj.ImageMask != "" && !e.images[obj.ImageMask]) {
+		if e.images[obj.ResourceID].X == 0 || (obj.ImageMask != "" && e.images[obj.ImageMask].X == 0) {
 			return GraphicObject{}, fmt.Errorf("image resource not found")
 		}
 		if obj.Border != nil {
@@ -720,6 +720,7 @@ func transformEditorObject(object GraphicObject, dx, dy, scale float64) (Graphic
 			if obj.layout != nil {
 				layout := *obj.layout
 				layout.options.LineHeight *= scale
+				layout.options.LetterSpacing *= scale
 				obj.layout = &layout
 			}
 			if obj.LineWidth == 0 && obj.Stroke != nil && *obj.Stroke {
@@ -756,10 +757,10 @@ func transformEditorObject(object GraphicObject, dx, dy, scale float64) (Graphic
 	return object, nil
 }
 
-// ReplaceImage 替换图片资源，保留对象位置、尺寸、变换和绘制顺序
+// ReplaceImage 替换图片资源，保留对象标识和绘制顺序，一次撤销恢复资源及布局。
-// 入参: page 页面索引, id 图片对象标识, data PNG或JPEG数据
+// 入参: page 页面索引, id 图片对象标识, data PNG或JPEG数据, fit 为contain、cover或空，空值保留原变换和裁剪
 // 返回: error 错误信息
-func (e *Editor) ReplaceImage(page int, id string, data []byte) error {
+func (e *Editor) ReplaceImage(page int, id string, data []byte, fit string) error {
 	object, err := e.Object(page, id)
 	if err != nil {
 		return err
@@ -771,6 +772,11 @@ func (e *Editor) ReplaceImage(page int, id string, data []byte) error {
 	if err != nil {
 		return err
 	}
+	if fit != "" {
+		if err := e.fitImage(&object.ImageObject, fit); err != nil {
+			return err
+		}
+	}
 	return e.UpdateObject(page, id, object)
 }
 
@@ -819,6 +825,9 @@ func (e *Editor) LayoutText(obj *TextObject, value string, options TextLayout) e
 	if !finite(lineHeight) || lineHeight < 0 {
 		return fmt.Errorf("line height must be finite and nonnegative")
 	}
+	if !finite(options.LetterSpacing) {
+		return fmt.Errorf("letter spacing must be finite")
+	}
 	if !slices.Contains([]string{"", "left", "center", "right", "justify"}, options.Align) {
 		return fmt.Errorf("invalid text alignment %q", options.Align)
 	}
@@ -849,13 +858,16 @@ func (e *Editor) LayoutText(obj *TextObject, value string, options TextLayout) e
 				return fmt.Errorf("font does not contain U+%04X", char)
 			}
 			advances[i] = float64(sfnt.GlyphAdvance(glyph)) * unit * hScale
-			if !finite(advances[i]) {
+		}
+		spaceTextAdvances(runes, advances, options.LetterSpacing)
+		for _, advance := range advances {
+			if !finite(advance) {
 				return fmt.Errorf("text advance exceeds finite range")
 			}
 		}
-		lines := breakTextLines(runes, advances, width, options.Wrap)
+		lines := breakTextLines(runes, advances, width, options.Wrap, options.LetterSpacing)
 		for i, line := range lines {
-			x, deltas := alignTextLine(runes[line[0]:line[1]], advances[line[0]:line[1]], width, options.Align, i+1 < len(lines))
+			x, deltas := alignTextLine(runes[line[0]:line[1]], advances[line[0]:line[1]], width, options.Align, i+1 < len(lines), options.LetterSpacing)
 			y := float64(ascender)*unit + float64(len(codes))*lineHeight
 			if !finite(x) || !finite(y) {
 				return fmt.Errorf("text position exceeds finite range")

ofdgo_editor_text.go

@@ -21,11 +21,13 @@ import (
 )
 
 // TextLayout 本地横向段落选项，Wrap按CTM变换前的边界宽度折行，Align为left、center、right或justify。
-// LineHeight为毫米单位的基线间距，0使用字体度量；零值保持显式换行和左对齐。
+// LineHeight为毫米单位的基线间距，0使用字体度量；LetterSpacing为字素间的附加毫米间距，可为负。
+// 零值保持显式换行和左对齐。
 type TextLayout struct {
 	Wrap          bool
 	Align         string
 	LineHeight    float64
+	LetterSpacing float64
 }
 
 // textLayout 保存编辑中的原文与选项，不写入OFD，也不参与渲染。
@@ -45,9 +47,9 @@ func (obj TextObject) TextLayout() (string, TextLayout) {
 }
 
 // breakTextLines 优先使用Unicode断行机会，过长词仅在字素边界折行，不丢弃空白。
-// 入参: runes 段落字符, advances 各字符步进, width 本地排版宽度, wrap 是否自动折行
+// 入参: runes 段落字符, advances 含字距的字符步进, width 本地排版宽度, wrap 是否自动折行, spacing 附加字距
 // 返回: [][2]int 各行的字符起止索引，左闭右开
-func breakTextLines(runes []rune, advances []float64, width float64, wrap bool) [][2]int {
+func breakTextLines(runes []rune, advances []float64, width float64, wrap bool, spacing float64) [][2]int {
 	if !wrap || len(runes) == 0 {
 		return [][2]int{{0, len(runes)}}
 	}
@@ -76,7 +78,11 @@ func breakTextLines(runes []rune, advances []float64, width float64, wrap bool)
 			for visible > start && runes[visible-1] == ' ' {
 				visible--
 			}
-			if sums[visible]-sums[start] > width && end > start {
+			length := sums[visible] - sums[start]
+			if visible > start {
+				length -= spacing
+			}
+			if length > width && end > start {
 				break
 			}
 			end = candidate
@@ -84,7 +90,7 @@ func breakTextLines(runes []rune, advances []float64, width float64, wrap bool)
 			if breaks[end] {
 				legal = end
 			}
-			if sums[visible]-sums[start] > width {
+			if length > width {
 				break
 			}
 		}
@@ -101,9 +107,9 @@ func breakTextLines(runes []rune, advances []float64, width float64, wrap bool)
 }
 
 // alignTextLine 将段落对齐转换为标准X和DeltaX，两端对齐保留段落末行左对齐。
-// 入参: runes 行内字符, advances 各字符步进, width 本地排版宽度, alignment 对齐方式, justify 是否允许本行两端对齐
+// 入参: runes 行内字符, advances 含字距的字符步进, width 本地排版宽度, alignment 对齐方式, justify 是否允许本行两端对齐, spacing 附加字距
 // 返回: float64 行首X坐标, string 字符间的DeltaX序列
-func alignTextLine(runes []rune, advances []float64, width float64, alignment string, justify bool) (float64, string) {
+func alignTextLine(runes []rune, advances []float64, width float64, alignment string, justify bool, spacing float64) (float64, string) {
 	end := len(runes)
 	for end > 0 && runes[end-1] == ' ' {
 		end--
@@ -112,6 +118,9 @@ func alignTextLine(runes []rune, advances []float64, width float64, alignment st
 	for _, advance := range advances[:end] {
 		length += advance
 	}
+	if end > 0 {
+		length -= spacing
+	}
 	x, extra := 0.0, max(0, width-length)
 	if alignment == "center" {
 		x = extra / 2
@@ -140,3 +149,17 @@ func alignTextLine(runes []rune, advances []float64, width float64, alignment st
 	}
 	return x, strings.Join(deltas, " ")
 }
+
+// spaceTextAdvances 将字距加入各字素末尾，不拆散组合字符。
+// 入参: runes 段落字符, advances 待更新的字符步进, spacing 附加毫米字距
+func spaceTextAdvances(runes []rune, advances []float64, spacing float64) {
+	if spacing == 0 {
+		return
+	}
+	var seg segmenter.Segmenter
+	seg.Init(runes)
+	for it := seg.GraphemeIterator(); it.Next(); {
+		cluster := it.Grapheme()
+		advances[cluster.Offset+len(cluster.Text)-1] += spacing
+	}
+}

ofdgo_editor_transform.go

@@ -16,6 +16,7 @@ package ofdgo
 
 import (
 	"fmt"
+	"math"
 	"slices"
 )
 
@@ -152,6 +153,16 @@ func (e *Editor) CropImage(page int, id string, box Box) error {
 		return fmt.Errorf("object %q is not an image", id)
 	}
 	image := &object.ImageObject
+	if err := cropImageObject(image, box); err != nil {
+		return err
+	}
+	return e.UpdateObject(page, id, object)
+}
+
+// cropImageObject 更新图片副本的裁剪和局部坐标，不修改资源。
+// 入参: image 图片对象副本, box 页面毫米坐标中的保留范围
+// 返回: error 错误信息
+func cropImageObject(image *ImageObject, box Box) error {
 	full, err := image.ImageBounds()
 	if err != nil {
 		return err
@@ -181,9 +192,66 @@ func (e *Editor) CropImage(page int, id string, box Box) error {
 		path.Fill, path.Stroke = &fill, &stroke
 		image.Clips = &Clips{Clip: []Clip{{Area: []ClipArea{{CTM: inverse.String(), Path: []PathObject{path}}}}}}
 	}
+	return nil
+}
+
+// FitImage 按原始像素比例居中适应或填充当前Boundary，保留直角旋转及镜像方向。
+// 保留原始图片，不重采样；重设裁剪，一次撤销恢复原布局。
+// 入参: page 页面索引, id 图片对象标识, mode 为contain（完整显示）或cover（填满裁剪）
+// 返回: error 错误信息
+func (e *Editor) FitImage(page int, id, mode string) error {
+	object, err := e.Object(page, id)
+	if err != nil {
+		return err
+	}
+	if object.Type != "ImageObject" {
+		return fmt.Errorf("object %q is not an image", id)
+	}
+	if err := e.fitImage(&object.ImageObject, mode); err != nil {
+		return err
+	}
 	return e.UpdateObject(page, id, object)
 }
 
+// fitImage 将原始像素比例应用到当前图片框，适应时保留空白，填充时裁掉超出部分。
+// 入参: obj 图片对象副本, mode 为contain或cover
+// 返回: error 错误信息
+func (e *Editor) fitImage(obj *ImageObject, mode string) error {
+	if mode != "contain" && mode != "cover" {
+		return fmt.Errorf("invalid image fit %q", mode)
+	}
+	box, err := creationBox(obj.Boundary)
+	if err != nil {
+		return err
+	}
+	m := NewMatrix(obj.CTM)
+	if !axisAlignedMatrix(m) {
+		return fmt.Errorf("image fitting requires an axis-aligned transform")
+	}
+	size := e.images[obj.ResourceID]
+	w, h := float64(size.X), float64(size.Y)
+	if m.a == 0 {
+		w, h = h, w
+	}
+	scale := math.Min(box.W/w, box.H/h)
+	if mode == "cover" {
+		scale = math.Max(box.W/w, box.H/h)
+	}
+	if m.a == 0 {
+		m.b, m.c = math.Copysign(float64(size.X)*scale, m.b), math.Copysign(float64(size.Y)*scale, m.c)
+	} else {
+		m.a, m.d = math.Copysign(w*scale, m.a), math.Copysign(h*scale, m.d)
+	}
+	m.e, m.f = 0, 0
+	full := m.TransformBox(Box{W: 1, H: 1})
+	m.e, m.f = (box.W-full.W)/2-full.X, (box.H-full.H)/2-full.Y
+	obj.CTM, obj.Clips = m.String(), nil
+	if mode == "cover" {
+		return cropImageObject(obj, box)
+	}
+	return nil
+}
+
 // TextFrame 将对象Boundary逆变换到本地坐标并返回轴对齐边界。
 // 直角旋转与翻转不改变本地段落宽度。
 // 返回: Box 对象本地坐标中的边界, error 错误信息