Android 画笔Paint
windows7
8年前
<p>了解Android Paint，一篇就够。引用Aige《 自定义控件其实很简单 》系列博客的话“很多时候你压根不需要了解太多原理，只需站在巨人的丁丁上即可”，所谓前人种树后人好乘凉，这里记录下我的实践结果。</p> <p>我们可以通过Paint中setter方法来为画笔设置属性：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/26463eb336c38696a0c93ed48551b5cb.jpg"></p> <p style="text-align:center"><img src="https://simg.open-open.com/show/949c3afeebf1cb0a0fa7e3c1bc75ca82.jpg"> <img src="https://simg.open-open.com/show/47318437494d500ba04812ca55583ab0.jpg"></p> <p>浩浩荡荡来将这些方法一一过一遍：</p> <h2><strong>set</strong></h2> <pre> <code class="language-java">void set(Paint src)</code></pre> <p>为当前画笔copy一个画笔</p> <h2><strong>setARGB</strong></h2> <pre> <code class="language-java">void setARGB(int a, int r, int g, int b)</code></pre> <p>设置Paint对象颜色，a代表透明度，r，g，b代表颜色值</p> <p>插播：RGB与十六进制区别</p> <p>一般在xml里定义颜色可以直接写:</p> <pre> <code class="language-java">android:textColor="#FF6281"</code></pre> <p>但是在code代码中就必须写成这样:</p> <pre> <code class="language-java">text.setTextColor(0xffff6281);</code></pre> <p>xml中透明度写不写无所谓,默认是ff不透明，但是代码中用十六进制0x来表示，就必须跟上ff透明度，不然会默认00全透明。</p> <h2><strong>setAlpha</strong></h2> <pre> <code class="language-java">void setAlpha(int a)</code></pre> <p>设置alpha透明度，范围为0~255</p> <h2><strong>setAntiAlias</strong></h2> <pre> <code class="language-java">void setAntiAlias(boolean aa)</code></pre> <p>是否抗锯齿</p> <h2><strong>setColor</strong></h2> <pre> <code class="language-java">void setColor(int color)</code></pre> <p>设置paint颜色</p> <h2><strong>setColorFilter</strong></h2> <pre> <code class="language-java">ColorFilter setColorFilter (ColorFilter filter)</code></pre> <p>设置颜色过滤， ColorFilter 有三个子类去实现ColorMatrixColorFilter、LightingColorFilter和PorterDuffColorFilter</p> <h2><strong>ColorMatrixColorFilter</strong></h2> <pre> <code class="language-java">public class PaintCanvas extends View { private Paint mPaint; //省略构造方法 private void init() { mPaint = new Paint(); mPaint.setAntiAlias(true); // 生成色彩矩阵 ColorMatrix colorMatrix = new ColorMatrix(new float[]{ 0.5F, 0, 0, 0, 0, 0, 0.5F, 0, 0, 0, 0, 0, 0.5F, 0, 0, 0, 0, 0, 1, 0, }); mPaint.setColorFilter(new ColorMatrixColorFilter(colorMatrix)); } @Override protected void onDraw(Canvas canvas) { Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.logo); canvas.drawBitmap(bitmap, 0, 0, mPaint); } }</code></pre> <p>第一行表示的R（红色）的向量，第二行表示的G（绿色）的向量，第三行表示的B（蓝色）的向量，最后一行表示A（透明度）的向量，这一顺序必须要正确不能混淆！这个矩阵不同的位置表示的RGBA值，其范围在0.0F至2.0F之间，1为保持原图的RGB值。每一行的第五列数字表示偏移值。</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/8ffb6a665da38ef20c987144bd2481f8.jpg"></p> <p>这是原图效果，增加ColorMatrix，效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/93dc6f5e3949226d1dd36896a31fe73a.jpg"></p> <h2><strong>LightingColorFilter</strong></h2> <p>只有一个构造方法， LightingColorFilter (int mul, int add) ，参数1：mul全称是colorMultiply意为色彩倍增；参数2：add全称是colorAdd意为色彩添加，这两个值都是16进制的色彩值0xAARRGGBB。</p> <pre> <code class="language-java">// 设置颜色过滤,去掉绿色 mPaint.setColorFilter(new LightingColorFilter(0xFFFF00FF, 0x00000000));</code></pre> <p>效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/3fcaa2f6cce211915a9e74ac662f1b82.jpg"></p> <h2><strong>PorterDuffColorFilter</strong></h2> <p>也只有一个构造方法， PorterDuffColorFilter (int color, PorterDuff.Mode mode) ，参数1：16进制表示的颜色值；参数2：PorterDuff内部类Mode中的一个常量值，这个值表示混合模式。</p> <pre> <code class="language-java">// 设置颜色过滤,Color的值设为红色，模式PorterDuff.Mode.DARKEN变暗 mPaint.setColorFilter(new PorterDuffColorFilter(Color.RED, PorterDuff.Mode.DARKEN));</code></pre> <p>效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/19766c03d0e38df30d931cfbe9f7a57c.jpg"></p> <p>混合模式还有很多，不仅是应用于图像色彩混合，还应用于图形混合。</p> <h2><strong>setDither</strong></h2> <pre> <code class="language-java">void setDither(boolean dither)</code></pre> <p>设定是否使用图像抖动处理，会使绘制出来的图片颜色更加平滑和饱满，图像更加清晰</p> <h2><strong>setFakeBoldText</strong></h2> <pre> <code class="language-java">void setFakeBoldText(boolean fakeBoldText)</code></pre> <p>设置伪粗体文本</p> <h2><strong>setFilterBitmap</strong></h2> <pre> <code class="language-java">void setFilterBitmap(boolean filter)</code></pre> <p>设置位图进行滤波处理</p> <h2><strong>setHinting</strong></h2> <pre> <code class="language-java">void setHinting (int mode)</code></pre> <p>Added in API level 14，设置暗示模式，HINTING_OFF 或 HINTING_ON</p> <h2><strong>setLetterSpacing</strong></h2> <pre> <code class="language-java">void setLetterSpacing (float letterSpacing)</code></pre> <p>Added in API level 21，设置文本字母间距，默认0，负值收紧文本</p> <h2><strong>setLinearText</strong></h2> <pre> <code class="language-java">void setLinearText(boolean linearText)</code></pre> <p>设置线性文本</p> <h2><strong>setMaskFilter</strong></h2> <pre> <code class="language-java">MaskFilter setMaskFilter (MaskFilter maskfilter)</code></pre> <p>设置滤镜的效果， <a href="/misc/goto?guid=4959722862673959030" rel="nofollow,noindex">MaskFilter</a> 有两个子类实现BlurMaskFilter, EmbossMaskFilter</p> <h2><strong>BlurMaskFilter</strong></h2> <p>设置画笔模糊阴影效果</p> <pre> <code class="language-java">mPaint.setMaskFilter(new BlurMaskFilter(20f, BlurMaskFilter.Blur.SOLID));</code></pre> <p>参数1：模糊延伸半径，必须>0；</p> <p>参数2：有四种枚举</p> <p>NORMAL，同时绘制图形本身内容+内阴影+外阴影,正常阴影效果</p> <p>INNER，绘制图形内容本身+内阴影，不绘制外阴影</p> <p>OUTER，不绘制图形内容以及内阴影，只绘制外阴影</p> <p>SOLID，只绘制外阴影和图形内容本身，不绘制内阴影</p> <p>BlurMaskFilter绘制的Bitmap基本完全不受影响</p> <p>四种枚举效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/dccb0959895cfda8852bb25d998667d5.jpg"></p> <p style="text-align:center"><img src="https://simg.open-open.com/show/15905ac3530af06d49b612bf14979aee.jpg"></p> <p style="text-align:center"><img src="https://simg.open-open.com/show/ec48b2b3300abfe45354b5ac8678b510.jpg"></p> <p style="text-align:center"><img src="https://simg.open-open.com/show/d72ec5fdbb8be1ddb057151369c4dc0a.jpg"></p> <h2><strong>EmbossMaskFilter</strong></h2> <pre> <code class="language-java">//Paint的setMaskFilter不被GPU支持,为了确保画笔的setMaskFilter能供起效，我们需要禁用掉GPU硬件加速或AndroidManifest.xml文件中设置android:hardwareAccelerated为false if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { //View从API Level 11才加入setLayerType方法 //设置软件渲染模式绘图 this.setLayerType(View.LAYER_TYPE_SOFTWARE, null); } //设置浮雕滤镜效果，参数1：光源指定方向；参数2:环境光亮度，取值0-1,值越小越暗；参数3：镜面高光反射系数，值越小反射越强；参数4：模糊延伸半径 mPaint.setMaskFilter(new EmbossMaskFilter(new float[]{1, 1, 1}, 0.4f, 8f, 3f));</code></pre> <p>效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/5c1053c02497867652039215efd558ef.jpg"></p> <h2><strong>setPathEffect</strong></h2> <pre> <code class="language-java">PathEffect setPathEffect(PathEffect effect)</code></pre> <p>设置路径效果， PathEffect 有6个子类实现ComposePathEffect, CornerPathEffect, DashPathEffect, DiscretePathEffect, PathDashPathEffect, SumPathEffect</p> <p>具体代码：</p> <pre> <code class="language-java">public class PaintCanvas extends View { private Paint mPaint; // 路径对象 private Path mPath; private PathEffect[] pathEffects = new PathEffect[7]; private float mPhase=5; //省略构造方法 private void init() { mPaint = new Paint(); mPaint.setStyle(Paint.Style.STROKE); mPaint.setStrokeWidth(5); mPaint.setAntiAlias(true); initPath(); } private void initPath() { // 实例化路径 mPath = new Path(); // 定义路径的起点 mPath.moveTo(10, 50); // 定义路径的各个点 for (int i = 0; i <= 30; i++) { mPath.lineTo(i * 35, (float) (Math.random() * 100)); } //什么都不处理 pathEffects[0] = null; //参数1：线段之间的圆滑程度 pathEffects[1] = new CornerPathEffect(10); //参数1：间隔线条长度(length>=2)，如float[] {20, 10}的偶数参数20定义了我们第一条实线的长度， //而奇数参数10则表示第一条虚线的长度，后面不再有数据则重复第一个数以此往复循环；参数2：虚实线间距 pathEffects[2] = new DashPathEffect(new float[]{20, 10}, mPhase); //参数1:值越小杂点越密集；参数2:杂点突出的大小，值越大突出的距离越大 pathEffects[3] = new DiscretePathEffect(5.0f, 10.0f); Path path = new Path(); path.addRect(0, 0, 8, 8, Path.Direction.CCW); //定义路径虚线的样式,参数1：path；参数2：实线的长度；参数3：虚实线间距 pathEffects[4] = new PathDashPathEffect(path, 20, mPhase, PathDashPathEffect.Style.ROTATE); pathEffects[5] = new ComposePathEffect(pathEffects[2], pathEffects[4]); //ComposePathEffect和SumPathEffect都可以用来组合两种路径效果,具体区别（不知道如何描述）小伙伴们自己试试 pathEffects[6] = new SumPathEffect(pathEffects[4], pathEffects[3]); } @Override protected void onDraw(Canvas canvas) { /* * 绘制路径 */ for (int i = 0; i < pathEffects.length; i++) { mPaint.setPathEffect(pathEffects[i]); canvas.drawPath(mPath, mPaint); // 每绘制一条将画布向下平移250个像素 canvas.translate(0, 250); } } }</code></pre> <p>效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/9fcd97f17c368cde19c2761a0227db9c.png"></p> <h2><strong>setRasterizer</strong></h2> <p>Rasterizer setRasterizer(Rasterizer rasterizer)</p> <p>设置光栅化，API21已过时</p> <h2><strong>setShader</strong></h2> <pre> <code class="language-java">Shader setShader(Shader shader)</code></pre> <p>设置着色器， <a href="/misc/goto?guid=4959722862768017348" rel="nofollow,noindex">Shader</a> 子类实现有BitmapShader, ComposeShader, LinearGradient, RadialGradient, SweepGradient</p> <h2><strong>BitmapShader</strong></h2> <p>对图形进行渲染，构造方法：</p> <pre> <code class="language-java">BitmapShader (Bitmap bitmap,Shader.TileMode tileX,Shader.TileMode tileY)</code></pre> <p>tileX、tileY参数Shader.TileMode有三个：</p> <p>CLAMP 重复最后一个颜色至最后</p> <p>MIRROR 重复着色的图像水平或垂直方向已镜像方式填充会有翻转效果</p> <p>REPEAT 重复着色的图像水平或垂直方向</p> <p>设置tileX、tileY为Shader.TileMode.CLAMP</p> <pre> <code class="language-java">public class PaintCanvas extends View { private Paint mPaint; private Context mContext; private Bitmap mBitmap; private BitmapShader mShader; // 省略构造方法 private void init() { mBitmap = BitmapFactory.decodeResource(mContext.getResources(), R.mipmap.logo); mShader= new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP); mPaint = new Paint(); mPaint.setAntiAlias(true); } @Override protected void onDraw(Canvas canvas) { mPaint.setShader(mBitmapShader); canvas.drawCircle(500, 550, 500, mPaint); } }</code></pre> <p>效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/35cbdd522a256ba4ef3501d655a29046.jpg"></p> <p>设置tileX、tileY为Shader.TileMode.MIRROR</p> <p>效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/25590da3b6d1bcf5a547554013d8c649.jpg"></p> <p>设置tileX、tileY为Shader.TileMode.REPEAT</p> <p>效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/3a498524e379523479c2ddadb1fbd2c0.jpg"></p> <h2><strong>LinearGradient</strong></h2> <p>设置线性渐变效果，有两个构造函数</p> <pre> <code class="language-java">//坐标(x0,y0)渐变直线的起点，坐标(x1,y1)渐变直线的终点，color0和color1分别表示了渐变的起始颜色和终止颜色，TileMode也有CLAMP 、REPEAT 和 MIRROR三个取值 LinearGradient(float x0, float y0, float x1, float y1, int color0, int color1, Shader.TileMode tile) LinearGradient(float x0, float y0, float x1, float y1, int[] colors, float[] positions,Shader.TileMode tile)</code></pre> <p>例子：</p> <pre> <code class="language-java">public class PaintCanvas extends View { private Paint mPaint; private Context mContext; private Bitmap mBitmap; private Shader mShader; // 省略构造方法 private void init() { mShader = new LinearGradient(0, 0, 500, 500, Color.BLUE, Color.GREEN,Shader.TileMode.CLAMP); mPaint = new Paint(); mPaint.setAntiAlias(true); } @Override protected void onDraw(Canvas canvas) { mPaint.setShader(mBitmapShader); canvas.drawCircle(500, 550, 400, mPaint); } }</code></pre> <p>效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/84d22e81ed2a7baf15141a94eae828a6.jpg"></p> <p>设置REPEAT 和 MIRROR就不贴图片了，小伙伴们可以自己试试看看效果。</p> <h2><strong>RadialGrdient</strong></h2> <p>设置光束从中心向四周发散的辐射渐变效果，构造方法：</p> <pre> <code class="language-java">//坐标(centerX,centerY)中心点坐标，radius圆的半径，centerColor中心颜色，edgeColor圆的轮廓颜色，颜色逐渐从centerColor渐变到edgeColor，TileMode也有CLAMP 、REPEAT 和 MIRROR三个取值 RadialGradient(float centerX, float centerY, float radius, int centerColor, int edgeColor, Shader.TileMode tileMode) RadialGradient(float centerX, float centerY, float radius, int[] colors, float[] stops, Shader.TileMode tileMode)</code></pre> <p>例子：</p> <pre> <code class="language-java">public class PaintCanvas extends View { private Paint mPaint; private Context mContext; private Shader mShader; // 省略构造方法 private void init() { mShader = new RadialGradient(500, 500, 400, Color.BLUE, Color.GREEN, Shader.TileMode.CLAMP); mPaint = new Paint(); mPaint.setAntiAlias(true); } @Override protected void onDraw(Canvas canvas) { mPaint.setShader(mBitmapShader); canvas.drawCircle(500, 550, 400, mPaint); } }</code></pre> <p>效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/c1e8bb0ae78c6f965971de9e2cef1c76.jpg"></p> <p>设置REPEAT 和 MIRROR也不贴图片了。</p> <h2><strong>SweepGradient</strong></h2> <p>设置绕着某中心点进行360度旋转渐变效果，构造方法：</p> <pre> <code class="language-java">//坐标(cx,cy)决定了中心点的位置，会绕着该中心点进行360度旋转。color0表示的是起点的颜色，color1表示的是终点的颜色 SweepGradient(float cx, float cy, int color0, int color1) //坐标(cx,cy)决定了中心点的位置,colors颜色数组,position取值范围为[0,1]，0和1都表示3点钟位置，0.25表示6点钟位置，0.5表示9点钟位置，0.75表示12点钟位置，诸如此类 SweepGradient(float cx, float cy, int[] colors, float[] positions)</code></pre> <p>例子：</p> <pre> <code class="language-java">public class PaintCanvas extends View { private Paint mPaint; private Context mContext; private Shader mShader; // 省略构造方法 private void init() { mShader = new SweepGradient(500, 500, Color.BLUE, Color.GREEN); mPaint = new Paint(); mPaint.setAntiAlias(true); } @Override protected void onDraw(Canvas canvas) { mPaint.setShader(mBitmapShader); canvas.drawCircle(500, 550, 400, mPaint); } }</code></pre> <p>效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/80febe61919f579e16ee82bb653f37a9.jpg"></p> <h2><strong>ComposeShader</strong></h2> <p>混合，有两个构造函数</p> <pre> <code class="language-java">//shaderA对应下层图形，shaderB对应上层图形 ComposeShader(Shader shaderA, Shader shaderB, Xfermode mode) ComposeShader(Shader shaderA, Shader shaderB, PorterDuff.Mode mode)</code></pre> <p>例子：</p> <pre> <code class="language-java">public class PaintCanvas extends View { private Paint mPaint; private Context mContext; private Bitmap mBitmap; private Shader bitmapShader, linearGradient, composeShader; // 省略构造方法 private void init() { mBitmap = BitmapFactory.decodeResource(mContext.getResources(), R.mipmap.logo); bitmapShader = new BitmapShader(mBitmap, Shader.TileMode.MIRROR, Shader.TileMode.MIRROR); linearGradient = new LinearGradient(0, 0, mBitmap.getWidth(), mBitmap.getHeight(), Color.BLUE, Color.GREEN, Shader.TileMode.CLAMP); //bitmapShader对应下层图形，linearGradient对应上层图形，像素颜色混合采用MULTIPLY模式 composeShader = new ComposeShader(bitmapShader, linearGradient, PorterDuff.Mode.MULTIPLY); mPaint = new Paint(); mPaint.setAntiAlias(true); } @Override protected void onDraw(Canvas canvas) { mPaint.setShader(mBitmapShader); canvas.drawCircle(500, 550, 400, mPaint); } }</code></pre> <p>效果如下：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/0d0e0793bc6f167f7bc06778f46eed4a.jpg"></p> <h2><strong>setShadowLayer</strong></h2> <pre> <code class="language-java">void setShadowLayer(float radius, float dx, float dy, int shadowColor)</code></pre> <p>图形添加一个阴影层效果</p> <h2><strong>setStrikeThruText</strong></h2> <pre> <code class="language-java">void setStrikeThruText (boolean strikeThruText)</code></pre> <p>设置删除线</p> <h2><strong>setStrokeCap</strong></h2> <pre> <code class="language-java">void setStrokeCap (Paint.Cap cap)</code></pre> <p>当设置setStyle是Stroke或StrokeAndFill，设置笔刷的图形样式，如圆形样式Cap.ROUND或方形样式Cap.SQUARE</p> <h2><strong>setStrokeJoin</strong></h2> <pre> <code class="language-java">void setStrokeJoin (Paint.Join join)</code></pre> <p>当设置setStyle是Stroke或StrokeAndFill，设置绘制时各图形的结合方式，如影响矩形角的外轮廓</p> <h2><strong>setStrokeMiter</strong></h2> <pre> <code class="language-java">void setStrokeMiter (float miter)</code></pre> <p>当设置setStyle是Stroke或StrokeAndFill，设置斜切</p> <h2><strong>setStrokeWidth</strong></h2> <pre> <code class="language-java">void setStrokeWidth (float width)</code></pre> <p>当画笔样式为STROKE或FILL_OR_STROKE时，设置笔刷的粗细度</p> <h2><strong>setStyle</strong></h2> <pre> <code class="language-java">void setStyle (Paint.Style style)</code></pre> <p>设置画笔样式，画笔样式分三种：</p> <p>Paint.Style.STROKE：描边</p> <p>Paint.Style.FILL_AND_STROKE：描边并填充</p> <p>Paint.Style.FILL：填充</p> <h2><strong>setSubpixelText</strong></h2> <pre> <code class="language-java">void setSubpixelText (boolean subpixelText)</code></pre> <p>有助于文本在LCD屏幕上的显示效果</p> <h2><strong>setTextAlign</strong></h2> <pre> <code class="language-java">void setTextAlign(Paint.Align align)</code></pre> <p>设置文本对齐</p> <h2><strong>setTextScaleX</strong></h2> <pre> <code class="language-java">void setTextScaleX(float scaleX)</code></pre> <p>设置文本缩放倍数，1.0f为原始</p> <h2><strong>setTextSize</strong></h2> <pre> <code class="language-java">void setTextSize(float textSize)</code></pre> <p>设置字体大小</p> <h2><strong>setTextSkewX</strong></h2> <pre> <code class="language-java">void setTextSkewX (float skewX)</code></pre> <p>设置斜体文字，skewX为倾斜弧度，默认值0，大于0，向左斜，小于0，向右斜</p> <h2><strong>setTypeface</strong></h2> <pre> <code class="language-java">Typeface setTypeface(Typeface typeface)</code></pre> <p>设置字体，Typeface包含了字体的类型，粗细，还有倾斜、颜色等。</p> <pre> <code class="language-java">mPaint.setTypeface(Typeface.SANS_SERIF);</code></pre> <h2><strong>setUnderlineText</strong></h2> <pre> <code class="language-java">void setUnderlineText(boolean underlineText)</code></pre> <p>设置下划线</p> <h2><strong>setXfermode</strong></h2> <pre> <code class="language-java">Xfermode setXfermode (Xfermode xfermode)</code></pre> <p>设置图像混合模式， Xfermode 有个子类去实现PorterDuffXfermode</p> <h2><strong>PorterDuffXfermode</strong></h2> <p>构造方法 PorterDuffXfermode(PorterDuff.Mode mode) ，参数就是上面的提到的，图形混合模式如图：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/ecc59255a3acf879894298af1374de31.png"></p> <p>Dst：先画(下层)的图形；Src：后画(上层)的图形，然而被网上这张图片误导了，解释见 <a href="/misc/goto?guid=4959722862850817094" rel="nofollow,noindex">孙群博客</a> ，他也给了最终运行效果：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/d3dd2c15706d2d144962ea892ba15e73.jpg"></p> <p>我一一运行确实是如此，这里贴出Mode 为Screen代码：</p> <pre> <code class="language-java">public class PaintCanvas extends View { private Paint mPaint; private PorterDuffXfermode porterDuffXfermode;// 图形混合模式 private Context mContext; private Bitmap mBitmap; //省略构造方法 private void init() { mBitmap = BitmapFactory.decodeResource(mContext.getResources(), R.mipmap.logo); mPaint = new Paint(); mPaint.setAntiAlias(true); // 实例化混合模式 porterDuffXfermode = new PorterDuffXfermode(PorterDuff.Mode.SCREEN); } @Override protected void onDraw(Canvas canvas) { int canvasWidth = canvas.getWidth(); int canvasHeight = canvas.getHeight(); //新建一个layer,放置在canvas默认layer的上部，产生的layer初始时是完全透明的 int layerId = canvas.saveLayer(0, 0, canvasWidth, canvasHeight, null, Canvas.ALL_SAVE_FLAG); //dst是先画的图形 canvas.drawBitmap(mBitmap, 0, 0, mPaint); //设置混合模式 mPaint.setXfermode(porterDuffXfermode); //src是后画的图形 mPaint.setColor(0xFFFFCC44); canvas.drawCircle(600, 600, 200, mPaint); //还原混合模式 mPaint.setXfermode(null); //或canvas.restore()把这个layer绘制到canvas默认的layer上去 canvas.restoreToCount(layerId); } }</code></pre> <p style="text-align:center"><img src="https://simg.open-open.com/show/c8851551aa1df285e1d0a6daecd2734d.jpg"></p> <p> </p> <h2>最后</h2> <p>这篇文章真长，从开始写到最后的校对，花了很长时间，每段代码运行都截图上传。只能说实践是检验真理的唯一标准，不一定知道每个原理，都必须知道每个是什么样子的效果，记录完成方便自己日后查找，也方便大家哦，如果您能读到这篇文章的话。</p> <p> </p> <p>来自：http://www.androidchina.net/5406.html</p> <p> </p>