群英传笔记：自定义view一个音频跳动图的绘制

public class MyView extends View {
public MyView(Context context) {
super(context);
}

public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(measureWidth(widthMeasureSpec), measureHeight(heightMeasureSpec));

}

/**
* View测量
* EXACTLY:精确模式，指定具体数值。
* AT_MOST:最大模式，此时控件尺寸只要不超过父控件允许的最大值就可。
* UNSPECIFIED:不指定大小测量模式，通常情况下在绘制自定义view才使用。
* view默认onMeasure方法只支持EXACTLY，所以如果自定义如果不重写onMeasure方法
* 控件可以响应指定的具体宽高或者match_parent，如果要支持wrap_content就必须重写来指定wrap的大小
*
* @param measure
* @return
*/
private int measureWidth(int measure) {
//        MeasureSpec是一个32为的int值，使用位运算，是为了提高并优化效率。
int result = 0;
//        提取测量模式和大小
int specMode = MeasureSpec.getMode(measure);
int specSize = MeasureSpec.getSize(measure);
//        通过测量模式给出不同的测量值，当模式为EXACTLY，直接赋值
if (specMode == MeasureSpec.EXACTLY) {
result = specSize;
} else {
//            为其它模式时，先设置一个默认值，与默认值比较
result = 200;
if (specMode == MeasureSpec.AT_MOST) {
result = Math.min(result, specSize);
}
}
return result;
}

private int measureHeight(int measure) {
int result = 0;
//        提取测量模式和大小
int specMode = MeasureSpec.getMode(measure);
int specSize = MeasureSpec.getSize(measure);
if (specMode == MeasureSpec.EXACTLY) {
result = specSize;
} else {
result = 200;
if (specMode == MeasureSpec.AT_MOST) {
result = Math.min(result, specSize);
}
}
return result;
}

/**
* 绘图
*
* @param canvas
*/
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);
Bitmap bitmap1 = BitmapFactory.decodeResource(getResources(), R.mipmap.start);

canvas.drawBitmap(bitmap, 0, 0, null);
canvas.drawBitmap(bitmap1, 0, 0, null);

}

//    从xml加载组建后回调
@Override
protected void onFinishInflate() {
super.onFinishInflate();
}

//    组件大小改变时回调
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
}

//    回调该方法来确定现实的位置
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
}

//    监听到触摸事件时回调
@Override
public boolean onTouchEvent(MotionEvent event) {
return super.onTouchEvent(event);
}
}

public class MyRedioBit extends View {
private double random;
private int mWidth;
private int mRectheight;
private int mRectWidth;
private Paint paint;

public MyRedioBit(Context context) {
super(context);
}

public MyRedioBit(Context context, AttributeSet attrs) {
super(context, attrs);
}

public MyRedioBit(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);

}

private int mRectCount = 12;
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int offset = 10;
for (int i = 0; i < mRectCount; i++) {
random = Math.random();
float currentHeight = (float) (mRectheight * random);
canvas.drawRect((float) (mWidth * 0.4 / 2 + mRectWidth * i + offset)
, currentHeight, (float) (mWidth * 0.4 / 2 + mRectWidth * (i + 1)), mRectheight, paint);
}

//        通知view进行重绘
//        invalidate();
//        延迟绘制，每隔300ms进行重绘
postInvalidateDelayed(300);

}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mWidth = getWidth();
mRectheight = getHeight();
mRectWidth = ((int) (mWidth * 0.6 / mRectCount));
//        设置阴影
LinearGradient linearGradient = new LinearGradient(0, 0, mRectWidth, mRectheight, Color.YELLOW, Color.BLUE, Shader.TileMode.CLAMP);
paint = new Paint();
paint.setShader(linearGradient);
}
}