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https://github.com/golang/go
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118 lines
2.5 KiB
Go
118 lines
2.5 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package draw
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import "image"
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// A Color represents a color with 8-bit R, G, B, and A values,
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// packed into a uint32—0xRRGGBBAA—so that comparison
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// is defined on colors.
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// Color implements image.Color.
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// Color also implements image.Image: it is a
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// 10⁹x10⁹-pixel image of uniform color.
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type Color uint32
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// Check that Color implements image.Color and image.Image
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var _ image.Color = Black
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var _ image.Image = Black
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var (
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Opaque Color = 0xFFFFFFFF;
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Transparent Color = 0x00000000;
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Black Color = 0x000000FF;
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White Color = 0xFFFFFFFF;
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Red Color = 0xFF0000FF;
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Green Color = 0x00FF00FF;
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Blue Color = 0x0000FFFF;
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Cyan Color = 0x00FFFFFF;
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Magenta Color = 0xFF00FFFF;
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Yellow Color = 0xFFFF00FF;
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PaleYellow Color = 0xFFFFAAFF;
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DarkYellow Color = 0xEEEE9EFF;
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DarkGreen Color = 0x448844FF;
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PaleGreen Color = 0xAAFFAAFF;
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MedGreen Color = 0x88CC88FF;
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DarkBlue Color = 0x000055FF;
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PaleBlueGreen Color = 0xAAFFFFFF;
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PaleBlue Color = 0x0000BBFF;
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BlueGreen Color = 0x008888FF;
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GreyGreen Color = 0x55AAAAFF;
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PaleGreyGreen Color = 0x9EEEEEFF;
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YellowGreen Color = 0x99994CFF;
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MedBlue Color = 0x000099FF;
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GreyBlue Color = 0x005DBBFF;
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PaleGreyBlue Color = 0x4993DDFF;
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PurpleBlue Color = 0x8888CCFF;
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)
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func (c Color) RGBA() (r, g, b, a uint32) {
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x := uint32(c);
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r, g, b, a = x>>24, (x>>16)&0xFF, (x>>8)&0xFF, x&0xFF;
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r |= r<<8;
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r |= r<<16;
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g |= g<<8;
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g |= g<<16;
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b |= b<<8;
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b |= b<<16;
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a |= a<<8;
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a |= a<<16;
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return;
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}
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// SetAlpha returns the color obtained by changing
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// c's alpha value to a and scaling r, g, and b appropriately.
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func (c Color) SetAlpha(a uint8) Color {
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r, g, b, oa := c>>24, (c>>16)&0xFF, (c>>8)&0xFF, c&0xFF;
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if oa == 0 {
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return 0
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}
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r = r*Color(a)/oa;
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if r < 0 {
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r = 0;
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}
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if r > 0xFF {
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r = 0xFF;
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}
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g = g*Color(a)/oa;
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if g < 0 {
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g = 0;
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}
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if g > 0xFF {
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g = 0xFF;
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}
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b = b*Color(a)/oa;
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if b < 0 {
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b = 0;
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}
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if b > 0xFF {
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b = 0xFF;
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}
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return r<<24 | g<<16 | b<<8 | Color(a);
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}
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func (c Color) Width() int {
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return 1e9;
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}
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func (c Color) Height() int {
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return 1e9;
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}
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func (c Color) At(x, y int) image.Color {
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return c;
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}
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func toColor(color image.Color) image.Color {
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if c, ok := color.(Color); ok {
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return c;
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}
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r, g, b, a := color.RGBA();
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return Color(r>>24<<24 | g>>24<<16 | b>>24<<8 | a>>24);
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}
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func (c Color) ColorModel() image.ColorModel {
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return image.ColorModelFunc(toColor);
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}
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