最近较流行的效果 Android自定义View实现倾斜列表/图片

先看看效果图：

实现思路：擦除图片相应的角，然后层叠图片，产生倾斜效果

代码实现：

1、定义属性

在values文件夹下的attrs文件添加以下代码

<resources>
 <declare-styleable name="TiltView">
   <attr name="type" format="integer" />
 </declare-styleable>
</resources>

2、自定义布局

public class TiltView extends ImageView {

private int imageWidth;//图片宽度
 private int imageHeight;//图片高度
 private double angle = 10 * Math.PI / 180;//三角形角度
 private int triangleHeight;//三角形高度
 private Paint paint;//画笔
 private Path path;//绘制路径
 private int type;//倾斜图片的类型

public TiltView(Context context) {
   this(context, null);
 }

public TiltView(Context context, AttributeSet attrs) {
   this(context, attrs, 0);
 }

public TiltView(Context context, AttributeSet attrs, int defStyleAttr) {
   super(context, attrs, defStyleAttr);
   TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.TiltView);
   type = array.getInteger(R.styleable.TiltView_type, 1);
   array.recycle();
 }

//重测大小
 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
   super.onMeasure(widthMeasureSpec, heightMeasureSpec);
   imageWidth = measureSpec(widthMeasureSpec);
   imageHeight = measureSpec(heightMeasureSpec);
   setMeasuredDimension(imageWidth, imageHeight); //设置View的大小
   triangleHeight = (int) (Math.abs(Math.tan(angle) * imageHeight));
 }

//测量长度
 private int measureSpec(int measureSpec) {
   int minLength = 200;
   int mode = MeasureSpec.getMode(measureSpec);
   int length = MeasureSpec.getSize(measureSpec);

if (mode == MeasureSpec.AT_MOST) {
     length = Math.min(length, minLength);
   }
   return length;
 }

@Override
 protected void onDraw(Canvas canvas) {
   initPaint();

Bitmap mBitmap = Bitmap.createBitmap(imageWidth, imageHeight, Bitmap.Config.ARGB_8888); //初始化Bitmap
   Canvas mCanvas = new Canvas(mBitmap);//创建画布，并绘制mBitmap
   Bitmap mBackBitmap = ((BitmapDrawable) getDrawable()).getBitmap();
   mCanvas.drawBitmap(resizeBitmap(mBackBitmap), 0, 0, null);//绘制Bitmap

setTriangle();
   paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
   mCanvas.drawPath(path, paint);

canvas.drawBitmap(mBitmap, 0, 0, null);
 }

//初始化画笔
 private void initPaint() {
   paint = new Paint();
   paint.setDither(true);//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
   paint.setAntiAlias(true);//设置抗锯齿
   paint.setStrokeWidth(5);
   paint.setStyle(Paint.Style.FILL);
   paint.setStrokeCap(Paint.Cap.ROUND);
   paint.setStrokeJoin(Paint.Join.ROUND);//圆角
 }

//设置三角形区域
 private void setTriangle() {
   path = new Path();
   switch (type) {
     case 1://右下角
       path.moveTo(0, imageHeight);
       path.lineTo(imageWidth, imageHeight);
       path.lineTo(imageWidth, imageHeight - triangleHeight);
       path.lineTo(0, imageHeight);
       break;
     case 2://左上角+左下角
       path.moveTo(0, triangleHeight);
       path.lineTo(imageWidth, 0);
       path.lineTo(0, 0);
       path.lineTo(0, imageHeight);
       path.lineTo(imageWidth, imageHeight);
       path.lineTo(0, imageHeight - triangleHeight);
       break;
     case 3://右上角+右下角
       path.moveTo(imageWidth, triangleHeight);
       path.lineTo(0, 0);
       path.lineTo(imageWidth, 0);
       path.lineTo(imageWidth, imageHeight);
       path.lineTo(0, imageHeight);
       path.lineTo(imageWidth, imageHeight - triangleHeight);
       break;
     case 4://右上角
       path.moveTo(0, 0);
       path.lineTo(imageWidth, 0);
       path.lineTo(imageWidth, triangleHeight);
       path.lineTo(0, 0);
       break;
     case 5://左上角
       path.moveTo(0, 0);
       path.lineTo(imageWidth, 0);
       path.lineTo(0, triangleHeight);
       path.lineTo(0, 0);
       break;
   }
 }

//重新调节图片大小
 private Bitmap resizeBitmap(Bitmap bitmap) {
   int width = bitmap.getWidth();
   int height = bitmap.getHeight();
   // 设置想要的大小
   int newWidth = imageWidth;
   int newHeight = imageHeight;
   // 计算缩放比例
   float scaleWidth = ((float) newWidth) / width;
   float scaleHeight = ((float) newHeight) / height;
   // 取得想要缩放的matrix参数
   Matrix matrix = new Matrix();
   matrix.postScale(scaleWidth, scaleHeight);
   // 得到新的图片
   return Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);
 }

}

3、布局代码调用

//其中android:layout_marginTop="-15dp"对效果实现有很大的作用
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical">

<com.pengkv.may.widget.TiltView
   android:layout_width="match_parent"
   android:layout_height="100dp"
   android:src="@drawable/sample_0"
   app:type="1" />

<com.pengkv.may.widget.TiltView
   android:layout_width="match_parent"
   android:layout_height="100dp"
   android:layout_marginTop="-15dp"
   android:src="@drawable/sample_1"
   app:type="2" />

<com.pengkv.may.widget.TiltView
   android:layout_width="match_parent"
   android:layout_height="100dp"
   android:layout_marginTop="-15dp"
   android:src="@drawable/sample_2"
   app:type="4" />

</LinearLayout>