SurfaceView
- View适用于主动刷新，SurfaceView适用于被动刷新，例如频繁刷新
- View在主线程中对画面进行刷新，SurfaceView通常会在子线程进行页面刷新
- View绘制时没有使用双缓冲机制，SurfaceView在底层机制中实项了双缓冲机制
正弦曲线，绘画板
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98private void init() {
mSurfaceHolder = getHolder();
mSurfaceHolder.addCallback(this);
setFocusable(true);
setFocusableInTouchMode(true);
setKeepScreenOn(true);
// mSurfaceHolder.setFormat(PixelFormat.OPAQUE);
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setColor(Color.RED);
mPaint.setStyle(Paint.Style.STROKE);
mPath = new Path();
mDrawPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mDrawPaint.setColor(Color.RED);
mDrawPaint.setStyle(Paint.Style.STROKE);
mDrawPaint.setStrokeCap(Paint.Cap.ROUND);
mDrawPaint.setStrokeWidth(5);
mDrawPaint.setStrokeJoin(Paint.Join.ROUND);
mDrawPath = new Path();
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mPath.moveTo(0, getHeight() / 2);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
mIsDrawing = true;
Log.e("surfaceCreated", Thread.currentThread().getName());
new Thread(this).start();
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
mIsDrawing = false;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
int x = (int) event.getX();
int y = (int) event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mDrawPath.moveTo(x, y);
break;
case MotionEvent.ACTION_MOVE:
mDrawPath.lineTo(x, y);
break;
case MotionEvent.ACTION_UP:
break;
}
return true;
}
@Override
public void run() {
while (mIsDrawing) {
long start = System.currentTimeMillis();
draw();
long end = System.currentTimeMillis();
//100是经验值，取值范围50-100ms
if (end - start < 100) {
try {
Thread.sleep(100 - (end - start));
} catch (InterruptedException e) {
e.printStackTrace();
}
}
x += 1;
y = (int) (100 * Math.sin(x * 2 * Math.PI / 180) + 100);
mPath.lineTo(x, y);
}
}
private void draw() {
try {
//获得canvas图像
mCanvas = mSurfaceHolder.lockCanvas();
//surfaceview 背景
mCanvas.drawColor(Color.WHITE);
//绘制路径
mCanvas.drawPath(mPath, mPaint);
mCanvas.drawPath(mDrawPath, mDrawPaint);
} catch (Exception e) {
e.printStackTrace();
} finally {
//保证每次内容的提交
if (mCanvas != null) mSurfaceHolder.unlockCanvasAndPost(mCanvas);
}
}
