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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