一、drawing 是什么?
命名空间
- wpf:system.windows.media
- winforms:system.drawing(gdi+)
继承链(wpf)
- object → dispatcherobject → dependencyobject → freezable → animatable → drawing
常用派生类:
- geometrydrawing(用 path 画形状)
- imagedrawing(贴位图)
- videodrawing(播放视频)
- glyphrundrawing(文字)
- drawinggroup(容器,可组合其它 drawing)
特点
- 轻量级:只存“矢量指令”,不继承 uielement,不参与布局/事件路由。
- 可冻结(freeze):变为只读后可跨线程使用。
- 可序列化/导出为 xaml。
二、典型用法
- 直接放在控件里
- 用 drawingbrush 或 drawingimage 把 drawing 变成 brush/image,再赋给控件的 background、source 等属性。
- 在 drawingvisual 里绘制
- 适合自定义控件、命中测试、打印。
- 在 drawinggroup 里组合
- 把多个 drawing 套娃,实现复杂场景。
三、案例:画一个“带阴影的圆角矩形按钮”
目标:
- 圆角矩形(填充线性渐变、描边)
- 下方有一层模糊阴影(半透明黑圆角矩形)
- 鼠标悬停时整体高亮(动画改变渐变)
wpf:
<window x:class="demodrawing.mainwindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" title="drawing 示例" width="300" height="200"> <grid> <!-- 使用 drawingbrush 做背景 --> <rectangle x:name="btnrect" width="180" height="60" mouseenter="btnrect_mouseenter" mouseleave="btnrect_mouseleave"> <rectangle.resources> <!-- 阴影 drawing --> <geometrydrawing x:key="shadow" geometry="m 5,5 175,5 175,55 5,55 z" brush="#80000000"> <geometrydrawing.pen> <pen brush="transparent" thickness="1"/> </geometrydrawing.pen> </geometrydrawing> <!-- 按钮主体 drawing --> <geometrydrawing x:key="body" geometry="m 0,0 170,0 170,50 0,50 z"> <geometrydrawing.brush> <lineargradientbrush startpoint="0,0" endpoint="0,1"> <gradientstop offset="0" color="#ff4c9aff"/> <gradientstop offset="1" color="#ff0050dd"/> </lineargradientbrush> </geometrydrawing.brush> <geometrydrawing.pen> <pen brush="#ff003399" thickness="2"/> </geometrydrawing.pen> </geometrydrawing> <!-- 组合 drawinggroup --> <drawinggroup x:key="combined"> <!-- 先画阴影 --> <drawinggroup.children> <drawinggroup> <drawinggroup.children> <staticresource resourcekey="shadow"/> </drawinggroup.children> <drawinggroup.bitmapeffect> <blurbitmapeffect radius="5"/> </drawinggroup.bitmapeffect> </drawinggroup> <!-- 再画按钮主体 --> <staticresource resourcekey="body"/> </drawinggroup.children> </drawinggroup> <!-- 把 drawinggroup 变成 brush --> <drawingbrush x:key="btnbrush" drawing="{staticresource combined}"/> </rectangle.resources> <rectangle.fill> <staticresource resourcekey="btnbrush"/> </rectangle.fill> </rectangle> </grid> </window>
后台代码
public partial class mainwindow : window { public mainwindow() { initializecomponent(); } private void btnrect_mouseenter(object sender, mouseeventargs e) { // 找到 drawing 里的渐变刷 var rect = (rectangle)sender; var brush = (drawingbrush)rect.fill; var dg = (drawinggroup)brush.drawing; var body = (geometrydrawing)((drawinggroup)dg.children[1]).children[0]; var lg = (lineargradientbrush)body.brush; // 动画高亮 var da = new coloranimation(color.fromrgb(0x6f, 0xba, 0xff), timespan.frommilliseconds(300)); lg.gradientstops[0].beginanimation(gradientstop.colorproperty, da); } private void btnrect_mouseleave(object sender, mouseeventargs e) { var rect = (rectangle)sender; var brush = (drawingbrush)rect.fill; var dg = (drawinggroup)brush.drawing; var body = (geometrydrawing)((drawinggroup)dg.children[1]).children[0]; var lg = (lineargradientbrush)body.brush; var da = new coloranimation(color.fromrgb(0x4c, 0x9a, 0xff), timespan.frommilliseconds(300)); lg.gradientstops[0].beginanimation(gradientstop.colorproperty, da); } }
四、winforms(gdi+)对应写法
winforms 没有 drawing 类,而是 graphicspath + lineargradientbrush + bitmap 的“即时模式”绘制。核心步骤:
protected override void onpaint(painteventargs e) { var g = e.graphics; g.smoothingmode = smoothingmode.antialias; // 1. 阴影 using (var path = createroundrect(5, 5, 175, 55, 8)) using (var brush = new solidbrush(color.fromargb(128, 0, 0, 0))) using (var blur = new bitmap(180, 60)) { using (var g2 = graphics.fromimage(blur)) { g2.smoothingmode = smoothingmode.antialias; g2.fillpath(brush, path); } // 手动高斯模糊(略)... g.drawimage(blur, 0, 0); } // 2. 主体 using (var path = createroundrect(0, 0, 170, 50, 8)) using (var brush = new lineargradientbrush( new point(0, 0), new point(0, 50), color.fromargb(255, 0x4c, 0x9a, 0xff), color.fromargb(255, 0x00, 0x50, 0xdd))) using (var pen = new pen(color.fromargb(255, 0x00, 0x33, 0x99), 2)) { g.fillpath(brush, path); g.drawpath(pen, path); } } private graphicspath createroundrect(float x, float y, float w, float h, float r) { var gp = new graphicspath(); gp.addarc(x + w - r, y, r, r, 270, 90); gp.addarc(x + w - r, y + h - r, r, r, 0, 90); gp.addarc(x, y + h - r, r, r, 90, 90); gp.addarc(x, y, r, r, 180, 90); gp.closefigure(); return gp; }
- wpf 的 drawing 体系是“矢量指令树”,轻量、可缓存、可动画,适合高性能场景(千级图形)。
- 常用套路:geometrydrawing/drawinggroup → drawingbrush/drawingimage → shape 或 image 控件。
- winforms 没有 drawing 类,用 graphics 即时绘制;想缓存可用 bitmap/ metafile。
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