140 lines
3.4 KiB
Go
140 lines
3.4 KiB
Go
package vision
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import (
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"image"
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"image/color"
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"image/draw"
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)
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// Position 水印位置
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type Position int
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const (
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TopLeft Position = iota
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TopCenter
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TopRight
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LeftCenter
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Center
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RightCenter
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BottomLeft
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BottomCenter
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BottomRight
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)
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// Watermark 给画布添加图片水印
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// mark: 水印画布
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// pos: 位置
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// opacity: 透明度 (0.0 - 1.0)
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// padding: 边距
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// angle: 旋转角度 (弧度)
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func (c *Canvas) Watermark(mark *Canvas, pos Position, opacity float64, padding int, angle ...float64) {
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if mark == nil || opacity < 0.01 {
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return
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}
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w, h := c.Width(), c.Height()
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mw, mh := mark.Width(), mark.Height()
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var x, y int
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switch pos {
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case TopLeft:
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x, y = padding, padding
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case TopCenter:
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x, y = (w-mw)/2, padding
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case TopRight:
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x, y = w-mw-padding, padding
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case LeftCenter:
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x, y = padding, (h-mh)/2
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case Center:
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x, y = (w-mw)/2, (h-mh)/2
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case RightCenter:
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x, y = w-mw-padding, (h-mh)/2
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case BottomLeft:
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x, y = padding, h-mh-padding
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case BottomCenter:
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x, y = (w-mw)/2, h-mh-padding
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case BottomRight:
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x, y = w-mw-padding, h-mh-padding
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}
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c.dc.Push()
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if len(angle) > 0 && angle[0] != 0 {
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c.dc.RotateAbout(angle[0], float64(x+mw/2), float64(y+mh/2))
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}
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// 处理透明度
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if opacity >= 0.99 {
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c.dc.DrawImage(mark.dc.Image(), x, y)
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} else {
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mask := image.NewUniform(color.Alpha{uint8(255 * opacity)})
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draw.DrawMask(c.dc.Image().(draw.Image), mark.dc.Image().Bounds().Add(image.Pt(x, y)), mark.dc.Image(), image.Point{}, mask, image.Point{}, draw.Over)
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}
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c.dc.Pop()
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}
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// TileWatermark 平铺图片水印
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// spacing: 间距
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// angle: 旋转角度 (弧度)
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func (c *Canvas) TileWatermark(mark *Canvas, opacity float64, spacing int, angle float64) {
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if mark == nil || opacity < 0.01 {
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return
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}
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mw, mh := mark.Width(), mark.Height()
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w, h := c.Width(), c.Height()
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stepX := mw + spacing
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stepY := mh + spacing
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for y := -mh; y < h+mh; y += stepY {
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for x := -mw; x < w+mw; x += stepX {
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c.dc.Push()
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c.dc.RotateAbout(angle, float64(x+mw/2), float64(y+mh/2))
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if opacity >= 0.99 {
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c.dc.DrawImage(mark.dc.Image(), x, y)
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} else {
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mask := image.NewUniform(color.Alpha{uint8(255 * opacity)})
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draw.DrawMask(c.dc.Image().(draw.Image), mark.dc.Image().Bounds().Add(image.Pt(x, y)), mark.dc.Image(), image.Point{}, mask, image.Point{}, draw.Over)
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}
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c.dc.Pop()
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}
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}
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}
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// TextWatermark 给画布添加文字水印
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func (c *Canvas) TextWatermark(text string, pos Position, style *DrawStyle, opacity float64, padding int, angle ...float64) {
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// 创建一个临时画布来渲染文字，然后调用 Watermark
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c.dc.Push()
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tw, th := c.dc.MeasureString(text)
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temp := New(int(tw)+4, int(th)+4)
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if style != nil && style.FillColor != "" {
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temp.dc.SetColor(ParseColor(style.FillColor))
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} else {
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temp.dc.SetColor(color.Black)
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}
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temp.dc.DrawString(text, 2, th+2)
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ang := 0.0
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if len(angle) > 0 {
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ang = angle[0]
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}
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c.Watermark(temp, pos, opacity, padding, ang)
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c.dc.Pop()
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}
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// TileTextWatermark 平铺文字水印
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func (c *Canvas) TileTextWatermark(text string, style *DrawStyle, opacity float64, spacing int, angle float64) {
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c.dc.Push()
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tw, th := c.dc.MeasureString(text)
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temp := New(int(tw)+4, int(th)+4)
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if style != nil && style.FillColor != "" {
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temp.dc.SetColor(ParseColor(style.FillColor))
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} else {
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temp.dc.SetColor(color.Black)
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}
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temp.dc.DrawString(text, 2, th+2)
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c.TileWatermark(temp, opacity, spacing, angle)
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c.dc.Pop()
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}
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