mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 17:27:08 +08:00
241 lines
8.2 KiB
Go
241 lines
8.2 KiB
Go
// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ofdgo
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import (
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"bytes"
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"fmt"
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"image"
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"math"
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"github.com/tdewolff/canvas"
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canvasimage "github.com/tdewolff/canvas/image"
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"golang.org/x/image/draw"
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)
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// renderImage 渲染图片
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// 入参: ctx 画布上下文, obj 图片对象, pageH 页面高度, parentCTM 父级CTM, boundaryInCTM 边界是否参与父级CTM, parentClip 父级裁剪路径
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func (r *Renderer) renderImage(ctx *canvas.Context, obj ImageObject, pageH float64, parentCTM *Matrix, boundaryInCTM bool, parentClip *canvas.Path) {
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if r.textOnly {
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return
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}
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if _, ok := ctx.Renderer.(*boundsRenderer); ok {
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r.measureImage(ctx, obj, pageH, parentCTM, boundaryInCTM, parentClip)
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return
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}
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if obj.Visible != nil && !*obj.Visible {
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return
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}
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resPath, ok := r.Reader.ResMap[obj.ResourceID]
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if !ok {
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return
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}
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img, err := r.decodeImageResource(resPath)
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if err != nil {
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return
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}
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box, _ := ParseBox(obj.Boundary)
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if maskPath, ok := r.Reader.ResMap[obj.ImageMask]; ok {
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if mask, err := r.decodeImageResource(maskPath); err == nil {
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img = imageWithMask(img, mask)
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}
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}
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img = imageWithAlpha(img, obj.Alpha)
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imgBounds := img.Bounds()
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imgW, imgH := float64(imgBounds.Dx()), float64(imgBounds.Dy())
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if imgW <= 0 || imgH <= 0 {
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return
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}
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ctm := NewMatrix(obj.CTM)
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if obj.CTM == "" {
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ctm = Matrix{a: box.W, d: box.H}
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}
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localCTM := ctm
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var m canvas.Matrix
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if boundaryInCTM && parentCTM != nil {
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x0 := box.X + ctm.c + ctm.e
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y0 := box.Y + ctm.d + ctm.f
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m = canvas.Matrix{
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{(parentCTM.a*ctm.a + parentCTM.c*ctm.b) / imgW, -(parentCTM.a*ctm.c + parentCTM.c*ctm.d) / imgH, parentCTM.a*x0 + parentCTM.c*y0 + parentCTM.e},
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{-(parentCTM.b*ctm.a + parentCTM.d*ctm.b) / imgW, (parentCTM.b*ctm.c + parentCTM.d*ctm.d) / imgH, pageH - (parentCTM.b*x0 + parentCTM.d*y0 + parentCTM.f)},
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}
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} else {
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if parentCTM != nil {
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ctm = parentCTM.Multiply(ctm)
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}
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m = canvas.Matrix{
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{ctm.a / imgW, -ctm.c / imgH, box.X + ctm.c + ctm.e},
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{-ctm.b / imgW, ctm.d / imgH, pageH - box.Y - ctm.d - ctm.f},
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}
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}
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clipPath := intersectClipPath(parentClip, r.buildObjectClipPath(obj.Clips, pageH, box.X, box.Y, localCTM, parentCTM, boundaryInCTM))
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img = r.imageWithClip(img, clipPath, m, 96)
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m = m.Scale(imgW/float64(img.Bounds().Dx()), imgH/float64(img.Bounds().Dy()))
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img, pad := imageWithTransparentEdge(img)
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if pad > 0 {
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p := float64(pad)
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m[0][2] -= m[0][0]*p + m[0][1]*p
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m[1][2] -= m[1][0]*p + m[1][1]*p
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}
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ctx.RenderImage(r.canvasEncodedImage(img), ctx.CoordSystemView().Mul(ctx.View()).Mul(m))
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if obj.Border != nil {
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r.renderImageBorder(ctx, obj, box, pageH, parentCTM, boundaryInCTM, clipPath)
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}
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}
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// canvasEncodedImage 在Canvas输出边界保留原始编码，不重新压缩图片
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// 入参: img 库图片
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// 返回: image.Image Canvas可直接嵌入的图片
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func (r *Renderer) canvasEncodedImage(img image.Image) image.Image {
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source, ok := img.(*EncodedImage)
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if !ok {
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return img
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}
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state := r.canvasState()
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if encoded, ok := state.images[source]; ok {
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return encoded
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}
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var encoded *canvasimage.Image
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if source.format == "jpeg" {
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encoded, _ = canvasimage.NewJPEGImage(bytes.NewReader(source.Bytes()))
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} else {
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encoded, _ = canvasimage.NewPNGImage(bytes.NewReader(source.Bytes()))
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}
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encoded.Bytes = source.Bytes()
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state.images[source] = encoded
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return encoded
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}
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// renderImageBorder 渲染图像边框
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// 入参: ctx 画布上下文, obj 图片对象, box 图像边界, pageH 页面高度, parentCTM 父级CTM, boundaryInCTM 边界是否参与父级CTM, clipPath 裁剪路径
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func (r *Renderer) renderImageBorder(ctx *canvas.Context, obj ImageObject, box Box, pageH float64, parentCTM *Matrix, boundaryInCTM bool, clipPath *canvas.Path) {
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border := obj.Border
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width := defaultPathLineWidth
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if border.LineWidth != nil {
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width = *border.LineWidth
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}
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if width == 0 {
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return
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}
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w, h := box.W, box.H
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data := fmt.Sprintf("M 0 0 L %g 0 L %g %g L 0 %g C", w, w, h, h)
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rx, ry := min(border.HorizonalCornerRadius, w/2), min(border.VerticalCornerRadius, h/2)
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if rx > 0 && ry > 0 {
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data = fmt.Sprintf("M 0 %g A %g %g 0 0 1 %g 0 L %g 0 A %g %g 0 0 1 %g %g L %g %g A %g %g 0 0 1 %g %g L %g %g A %g %g 0 0 1 0 %g C",
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ry, rx, ry, rx, w-rx, rx, ry, w, ry, w, h-ry, rx, ry, w-rx, h, rx, h, rx, ry, h-ry)
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}
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r.renderPath(ctx, PathObject{
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Boundary: obj.Boundary,
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LineWidth: width,
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DashOffset: &border.DashOffset,
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DashPattern: border.DashPattern,
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Alpha: obj.Alpha,
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StrokeColor: border.BorderColor,
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AbbreviatedData: data,
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}, pageH, nil, parentCTM, boundaryInCTM, clipPath)
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}
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// imageWithClip 应用图片裁剪区域
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// 低分辨率图片按最低精度细化蒙版，细化后的像素上限16Mi，不降低原图分辨率
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// 入参: img 图片对象, clipPath 裁剪路径, m 图片变换矩阵, dpi 最低蒙版分辨率，0保留原图精度
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// 返回: image.Image 裁剪后的图片对象
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func (r *Renderer) imageWithClip(img image.Image, clipPath *canvas.Path, m canvas.Matrix, dpi float64) image.Image {
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if img == nil || clipPath == nil || m.Det() == 0 {
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return img
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}
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bounds := img.Bounds()
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w, h := bounds.Dx(), bounds.Dy()
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if w == 0 || h == 0 {
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return img
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}
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p0 := m.Dot(canvas.Point{})
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p1 := m.Dot(canvas.Point{X: float64(w)})
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p2 := m.Dot(canvas.Point{X: float64(w), Y: float64(h)})
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p3 := m.Dot(canvas.Point{Y: float64(h)})
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imagePath := &canvas.Path{}
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imagePath.MoveTo(p0.X, p0.Y)
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imagePath.LineTo(p1.X, p1.Y)
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imagePath.LineTo(p2.X, p2.Y)
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imagePath.LineTo(p3.X, p3.Y)
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imagePath.Close()
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if rect, ok := rectangularPath(clipPath); ok {
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if rect.Contains(imagePath.FastBounds()) {
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return img
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}
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} else if clipPath.Contains(imagePath) {
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return img
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}
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scale := math.Max(math.Hypot(m[0][0], m[1][0]), math.Hypot(m[0][1], m[1][1])) * dpi / 25.4
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scale = math.Min(scale, math.Sqrt((16<<20)/(float64(w)*float64(h))))
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if scale > 1 {
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nw, nh := int(float64(w)*scale), int(float64(h)*scale)
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resized := image.NewNRGBA(image.Rect(0, 0, nw, nh))
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draw.CatmullRom.Scale(resized, resized.Bounds(), imagePixelSource(img), bounds, draw.Src, nil)
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img = resized
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m = m.Scale(float64(w)/float64(nw), float64(h)/float64(nh))
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bounds, w, h = resized.Bounds(), nw, nh
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}
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clip := clipPath.Copy().Transform(m.Inv())
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compiler := &canvasPageCompiler{page: &RasterPage{Width: float64(w), Height: float64(h), DPI: 25.4}, geometry: r.backends.Geometry}
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ctx := canvas.NewContext(compiler)
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ctx.SetFillColor(canvas.White)
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ctx.SetStrokeColor(canvas.Transparent)
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ctx.DrawPath(0, 0, clip)
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if compiler.err != nil {
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r.renderError = compiler.err
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return img
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}
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if r.backends.Raster == nil {
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r.renderError = fmt.Errorf("image clip raster: %w", ErrBackendUnavailable)
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return img
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}
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result, err := r.backends.Raster.Render(compiler.page)
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if err != nil {
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r.renderError = err
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return img
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}
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mask, ok := result.(*image.RGBA)
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if !ok {
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mask = image.NewRGBA(image.Rect(0, 0, w, h))
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draw.Draw(mask, mask.Bounds(), result, result.Bounds().Min, draw.Src)
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}
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if mask.Opaque() {
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return img
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}
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source := imagePixelSource(img)
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out := &image.NRGBA{Pix: mask.Pix, Stride: mask.Stride, Rect: bounds}
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if src, ok := source.(*image.NRGBA); ok {
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for y := 0; y < h; y++ {
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offset := src.PixOffset(bounds.Min.X, bounds.Min.Y+y)
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row := out.Pix[y*out.Stride : y*out.Stride+w*4]
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pixels := src.Pix[offset : offset+w*4]
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for x := 0; x < len(row); x += 4 {
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copy(row[x:x+3], pixels[x:x+3])
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row[x+3] = uint8(int(pixels[x+3]) * int(row[x+3]) / 255)
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}
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}
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return out
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}
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for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
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for x := bounds.Min.X; x < bounds.Max.X; x++ {
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c := imageNRGBAAt(source, x, y)
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a := mask.RGBAAt(x-bounds.Min.X, y-bounds.Min.Y).A
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c.A = uint8(int(c.A) * int(a) / 255)
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out.SetNRGBA(x, y, c)
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}
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}
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return out
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}
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