效果图
效果图
知识点（自定义TextView）,重新方法
- onTouchEvent
- onDraw
1.自定义变量
private Bitmap mDownBitmap, mUpBitmap;//图片
private Paint mPaint; //画笔
private Canvas mCanvas; //画布
private Path mPath; //用于绘制复杂的图形轮廓，比如折线，圆弧以及各种复杂图案
2.初始化方法init()：
private void init() {
mPaint = new Paint();
mPaint.setAlpha(0);//画笔透明度为0
//使用DST_IN模式将路径绘制到前面覆盖的图层上
mPaint.setXfermode(
new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
mPaint.setStyle(Paint.Style.STROKE);
//笔触和连接处更加圆滑
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeWidth(50);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPath = new Path();
mDownBitmap = BitmapFactory.decodeResource(getResources(),
R.drawable.ic_launcher);
mUpBitmap = Bitmap.createBitmap(mDownBitmap.getWidth(),
mDownBitmap.getHeight(), Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mUpBitmap);
mCanvas.drawColor(Color.GRAY);
}
其中PorterDuffXfermode有16种混合模式的效果
效果图
3.重新onTouchEvent方法：
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mPath.reset();//清除path设置的所有属性
mPath.moveTo(event.getX(), event.getY());//将起始轮廓点移至x，y坐标点，默认情况为0,0点
break;
case MotionEvent.ACTION_MOVE:
mPath.lineTo(event.getX(), event.getY()); //用于从当前轮廓点绘制一条线段到x，y点
break;
}
mCanvas.drawPath(mPath, mPaint); //重新绘制Path
invalidate(); //刷新
return true;
}
4.重新onDraw方法：
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//绘制图片
canvas.drawBitmap(mDownBitmap, 0, 0, null);
canvas.drawBitmap(mUpBitmap, 0, 0, null);
}
完整版代码：
public class GuaGuaCard extends View {
private Bitmap mDownBitmap, mUpBitmap;//图片
private Paint mPaint; //画笔
private Canvas mCanvas; //画布
private Path mPath; //用于绘制复杂的图形轮廓，比如折线，圆弧以及各种复杂图案
public GuaGuaCard(Context context) {
super(context);
init();
}
public GuaGuaCard(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
init();
}
public GuaGuaCard(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
mPaint = new Paint();
mPaint.setAlpha(0);//画笔透明度为0
//使用DST_IN模式将路径绘制到前面覆盖的图层上
mPaint.setXfermode(
new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
mPaint.setStyle(Paint.Style.STROKE);
//笔触和连接处更加圆滑
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeWidth(50);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPath = new Path();
mDownBitmap = BitmapFactory.decodeResource(getResources(),
R.drawable.ic_launcher);
mUpBitmap = Bitmap.createBitmap(mDownBitmap.getWidth(),
mDownBitmap.getHeight(), Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mUpBitmap);
mCanvas.drawColor(Color.GRAY);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mPath.reset();//清除path设置的所有属性
mPath.moveTo(event.getX(), event.getY());//将起始轮廓点移至x，y坐标点，默认情况为0,0点
break;
case MotionEvent.ACTION_MOVE:
mPath.lineTo(event.getX(), event.getY()); //用于从当前轮廓点绘制一条线段到x，y点
break;
}
mCanvas.drawPath(mPath, mPaint); //重新绘制Path
invalidate(); //刷新
return true;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//绘制图片
canvas.drawBitmap(mDownBitmap, 0, 0, null);
canvas.drawBitmap(mUpBitmap, 0, 0, null);
}
}
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