feat(功能强化): 支持页面文字选择复制，优化选区显示

assets/webui/ofdgo.css

@@ -785,6 +785,34 @@ button.outline-link:hover {
 	transform-origin: 0 0;
 }
 
+.text-layer {
+	position: absolute;
+	inset: 0;
+	overflow: hidden;
+	color: transparent;
+	opacity: 0.24;
+	pointer-events: none;
+	-webkit-user-select: text;
+	user-select: text;
+	text-size-adjust: none;
+}
+
+.text-run > span {
+	position: absolute;
+	left: 0;
+	top: 0;
+	font: 100px/1 sans-serif;
+	white-space: pre;
+	transform-origin: 0 0;
+	cursor: text;
+	pointer-events: auto;
+}
+
+.text-run > span::selection {
+	color: transparent;
+	background: var(--accent);
+}
+
 .page-link {
 	position: absolute;
 }
@@ -833,6 +861,8 @@ button.outline-link:hover {
 	display: block;
 	max-width: none;
 	transform-origin: 0 0;
+	-webkit-user-select: none;
+	user-select: none;
 }
 
 .meta-list {

assets/webui/ofdgo.js

@@ -50,6 +50,7 @@ const state = {
 	continuous: false,
 	renderAnnotations: true,
 	pageCache: new Map(),
+	selectedPages: new Set(),
 	pageInFlight: new Map(),
 	pageRenderQueue: [],
 	pageRenderRunning: false,
@@ -194,6 +195,12 @@ el.fitButton.addEventListener("click", fitWidth);
 el.fitHeightButton.addEventListener("click", fitHeight);
 el.continuousButton.addEventListener("click", toggleContinuous);
 el.annotationButton.addEventListener("click", toggleAnnotations);
+document.addEventListener("copy", copySelection);
+document.addEventListener("selectionchange", () => {
+	for (const index of state.selectedPages) {
+		unmountPage(index);
+	}
+});
 el.pageExportFormat.addEventListener("change", () => updateDPIControl());
 el.exportPageButton.addEventListener("click", exportCurrentPage);
 el.exportButton.addEventListener("click", exportPDF);
@@ -1471,6 +1478,7 @@ function renderPageFlow() {
 
 function resetPageFlow() {
 	state.pageCache.clear();
+	state.selectedPages.clear();
 	state.visiblePages.clear();
 	for (const task of state.pageInFlight.values()) {
 		task.resolve(null);
@@ -1509,13 +1517,11 @@ function flowPageObserver() {
 				const index = Number.parseInt(entry.target.dataset.pageIndex, 10);
 				if (!entry.isIntersecting) {
 					state.visiblePages.delete(index);
-					if (entry.target.classList.contains("rendered")) {
+					unmountPage(index);
-						entry.target.querySelector(".page-surface").replaceChildren();
-						entry.target.classList.remove("rendered");
-					}
 					continue;
 				}
 				state.visiblePages.add(index);
+				state.selectedPages.delete(index);
 				renderFlowPage(index, { openSeq, priority: 4 });
 			}
 		}, {
@@ -1526,6 +1532,18 @@ function flowPageObserver() {
 	return state.pageObserver;
 }
 
+function unmountPage(index) {
+	const shell = pageShell(index);
+	const selection = document.getSelection();
+	if (selection.rangeCount && selection.getRangeAt(0).intersectsNode(shell)) {
+		state.selectedPages.add(index);
+		return;
+	}
+	shell.querySelector(".page-surface").replaceChildren();
+	shell.classList.remove("rendered");
+	state.selectedPages.delete(index);
+}
+
 async function renderFlowPage(index, options = {}) {
 	const openSeq = options.openSeq || state.openSeq;
 	if (openSeq !== state.openSeq) {
@@ -1638,6 +1656,7 @@ function mountPageSVG(index, page, openSeq = state.openSeq) {
 	const svg = parseSVG(page.svg, `p${openSeq}-${index}`);
 	svg.classList.add("ofd-svg");
 	surface.replaceChildren(svg);
+	surface.append(createTextLayer(page.text));
 	for (const link of page.links) {
 		let url;
 		try {
@@ -1668,6 +1687,64 @@ function mountPageSVG(index, page, openSeq = state.openSeq) {
 	}
 }
 
+function createTextLayer(text) {
+	const layer = document.createElement("div");
+	layer.className = "text-layer";
+	const measure = document.createElement("canvas").getContext("2d");
+	measure.font = "100px sans-serif";
+	for (const run of text.runs || []) {
+		const line = document.createElement("span");
+		line.className = "text-run";
+		const chars = Array.from(run.text);
+		for (const item of run.spans || []) {
+			const span = document.createElement("span");
+			span.textContent = chars.slice(item.start, item.end).join("");
+			const width = measure.measureText(span.textContent).width || 1;
+			const [a, b, c, d, e, f] = item.matrix.map((value) => value * MM_TO_PX);
+			span.style.transform = `matrix(${a / width}, ${b / width}, ${c / 100}, ${d / 100}, ${e}, ${f})`;
+			line.append(span);
+		}
+		layer.append(line);
+	}
+	return layer;
+}
+
+function copySelection(event) {
+	if (event.target.closest?.("input, textarea, [contenteditable]")) {
+		return;
+	}
+	const selection = document.getSelection();
+	if (selection.isCollapsed || !selection.rangeCount) {
+		return;
+	}
+	const range = selection.getRangeAt(0);
+	if (!el.svgHost.contains(range.startContainer) || !el.svgHost.contains(range.endContainer)) {
+		return;
+	}
+	const lines = [];
+	for (const run of el.svgHost.querySelectorAll(".text-run")) {
+		if (!range.intersectsNode(run)) {
+			continue;
+		}
+		const part = range.cloneRange();
+		if (!run.contains(part.startContainer)) {
+			part.setStart(run, 0);
+		}
+		if (!run.contains(part.endContainer)) {
+			part.setEnd(run, run.childNodes.length);
+		}
+		const text = part.cloneContents().textContent;
+		if (text) {
+			lines.push(text);
+		}
+	}
+	if (!lines.length) {
+		return;
+	}
+	event.clipboardData.setData("text/plain", lines.join("\n"));
+	event.preventDefault();
+}
+
 function markFlowPageError(index, err) {
 	const shell = pageShell(index);
 	if (!shell) {

internal/webui/wasm.go

@@ -164,6 +164,14 @@ func renderPage(args []js.Value) (any, error) {
 	if err != nil {
 		return nil, err
 	}
+	text, err := currentSession.PageText(args[0].Int())
+	if err != nil {
+		return nil, err
+	}
+	textData, err := json.Marshal(text)
+	if err != nil {
+		return nil, err
+	}
 	links := make([]any, len(page.Links))
 	for i, link := range page.Links {
 		links[i] = map[string]any{
@@ -182,6 +190,7 @@ func renderPage(args []js.Value) (any, error) {
 		"height": page.Height,
 		"svg":    page.SVG,
 		"links":  links,
+		"text":   js.Global().Get("JSON").Call("parse", string(textData)),
 	}), nil
 }
 

internal/webui/webui.go

@@ -270,10 +270,10 @@ func (s *Session) SetFonts(fonts []FontFile) error {
 	return nil
 }
 
-// SearchPage 搜索指定页面，复用当前会话的文字索引
+// PageText 获取指定页面文字，复用当前会话的文字索引
-// 入参: index 页面索引, query 搜索文字
+// 入参: index 页面索引
-// 返回: []ofdgo.TextMatch 匹配结果, error 错误信息
+// 返回: *ofdgo.PageText 页面文字, error 错误信息
-func (s *Session) SearchPage(index int, query string) ([]ofdgo.TextMatch, error) {
+func (s *Session) PageText(index int) (*ofdgo.PageText, error) {
 	text := s.textCache[index]
 	if text == nil {
 		_, page, err := s.pageContent(index)
@@ -286,6 +286,17 @@ func (s *Session) SearchPage(index int, query string) ([]ofdgo.TextMatch, error)
 		}
 		s.textCache[index] = text
 	}
+	return text, nil
+}
+
+// SearchPage 搜索指定页面，复用当前会话的文字索引
+// 入参: index 页面索引, query 搜索文字
+// 返回: []ofdgo.TextMatch 匹配结果, error 错误信息
+func (s *Session) SearchPage(index int, query string) ([]ofdgo.TextMatch, error) {
+	text, err := s.PageText(index)
+	if err != nil {
+		return nil, err
+	}
 	return text.Search(query), nil
 }
 

ofdgo_renderer_text.go

@@ -179,6 +179,10 @@ func (r *Renderer) renderText(ctx *canvas.Context, obj TextObject, pageH float64
 		return
 	}
 	face := ff.Face(sizePt, fillPaint, fontStyle, canvas.FontNormal)
+	var metrics canvas.FontMetrics
+	if textRun != nil {
+		metrics = face.Metrics()
+	}
 	glyphTransforms := r.textObjectGlyphTransforms(fontID, obj)
 	hasUnderline := strings.Contains(obj.Decoration, "Underline")
 	_, shadedFill := fillPaint.(canvas.Gradient)
@@ -291,6 +295,11 @@ func (r *Renderer) renderText(ctx *canvas.Context, obj TextObject, pageH float64
 					for j := spans[i][0]; j < spans[i][1]; j++ {
 						textRun.Boxes[textPos+j] = unionTextBox(textRun.Boxes[textPos+j], box)
 					}
+					bounds := canvas.Rect{Y0: -metrics.Descent, X1: glyphWidth, Y1: metrics.Ascent}
+					if !glyphPath.Empty() {
+						bounds = bounds.Add(glyphPath.Bounds())
+					}
+					textRun.addSpan(textPos+spans[i][0], textPos+spans[i][1], bounds, m.Scale(scaleX, 1), clipPath, pageH)
 				}
 				continue
 			}

ofdgo_search.go

@@ -31,9 +31,18 @@ type PageText struct {
 // TextRun 文本对象原文及逐字符区域，坐标以页面左上角为原点，单位为毫米
 // Boxes与Text的Unicode字符一一对应，缺少字体时使用文本对象区域
 type TextRun struct {
-	ID    string `json:"id"`
+	ID    string     `json:"id"`
-	Text  string `json:"text"`
+	Text  string     `json:"text"`
-	Boxes []Box  `json:"boxes"`
+	Boxes []Box      `json:"boxes"`
+	Spans []TextSpan `json:"spans"`
+}
+
+// TextSpan 可选文字区间，Start和End为Unicode字符偏移
+// Matrix依次为a、b、c、d、e、f，将单位矩形映射到页面左上角为原点的毫米坐标
+type TextSpan struct {
+	Start  int        `json:"start"`
+	End    int        `json:"end"`
+	Matrix [6]float64 `json:"matrix"`
 }
 
 // TextMatch 文字匹配结果，Run为文本对象索引，Start和End为原文Unicode字符区间
@@ -176,3 +185,36 @@ func unionTextBox(a, b Box) Box {
 	x, y := math.Min(a.X, b.X), math.Min(a.Y, b.Y)
 	return Box{X: x, Y: y, W: math.Max(a.X+a.W, b.X+b.W) - x, H: math.Max(a.Y+a.H, b.Y+b.H) - y}
 }
+
+// addSpan 收集字形选择区域，同一原文区间的多个字形合并为一项
+// 入参: start 起始字符, end 结束字符, bounds 字形布局区域, m 字形变换, clip 裁剪路径, pageH 页面高度
+func (run *TextRun) addSpan(start, end int, bounds canvas.Rect, m canvas.Matrix, clip *canvas.Path, pageH float64) {
+	if m.Det() == 0 {
+		return
+	}
+	if clip != nil {
+		path := canvas.Rectangle(bounds.W(), bounds.H()).Translate(bounds.X0, bounds.Y0).Transform(m)
+		path = applyClipPath(path, clip)
+		if path.Empty() {
+			return
+		}
+		bounds = path.Transform(m.Inv()).Bounds()
+	}
+	if bounds.W() < 0 || bounds.H() <= 0 {
+		return
+	}
+	m = canvas.Matrix{{1, 0, 0}, {0, -1, pageH}}.Mul(m).Translate(bounds.X0, bounds.Y1).Scale(bounds.W(), -bounds.H())
+	span := TextSpan{Start: start, End: end}
+	if n := len(run.Spans); n > 0 && run.Spans[n-1].Start == start && run.Spans[n-1].End == end {
+		span = run.Spans[n-1]
+		v := span.Matrix
+		previous := canvas.Matrix{{v[0], v[2], v[4]}, {v[1], v[3], v[5]}}
+		if previous.Det() != 0 {
+			bounds = canvas.Rect{X1: 1, Y1: 1}.Add(canvas.Rect{X1: 1, Y1: 1}.Transform(previous.Inv().Mul(m)))
+			m = previous.Translate(bounds.X0, bounds.Y0).Scale(bounds.W(), bounds.H())
+		}
+		run.Spans = run.Spans[:n-1]
+	}
+	span.Matrix = [6]float64{m[0][0], m[1][0], m[0][1], m[1][1], m[0][2], m[1][2]}
+	run.Spans = append(run.Spans, span)
+}