Android自定义View多种效果解析(android,roi,view,移动开发)

public class CustomeRectView extends View { private Paint mPiant;//定义画笔对象 private int rectColor;//矩形的颜色 private int rectHeight;//矩形的高度 private int rectWidth;//矩形的宽度 public CustomeRectView(Context context) { this(context, null); } public CustomeRectView(Context context, @Nullable AttributeSet attrs) { this(context, attrs, 0); } public CustomeRectView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); /** * 获取我们自定义的属性 */ TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.CustomeRectView, defStyleAttr, 0); int arrayCount = array.getIndexCount(); for (int i = 0; i < arrayCount; i++) { int index = array.getIndex(i); switch (index) { case R.styleable.CustomeRectView_rectColor: //getColor(int index，int defaultValue) rectColor=array.getColor(R.styleable.CustomeRectView_rectColor, Color.BLACK); break; case R.styleable.CustomeRectView_rectHeight: /** * 获取dimension值得时候会有3个不同的方法getDimension()、getDimensionPixelSize()和getDimenPixelOffset() * 结果值都是将资源文件中定义的dip值乘以屏幕密度,即rectHeight*屏幕密度，只是getDimension()返回的是float， * 其余两个返回的是int, 其中getDimensionPixelSize()返回的是实际数值的四舍五入, * 而getDimensionPixelOffset返回的是实际数值去掉后面的小数点; */ rectHeight=array.getDimensionPixelOffset(R.styleable.CustomeRectView_rectHeight,200); break; case R.styleable.CustomeRectView_rectWidth: rectWidth=array.getDimensionPixelOffset(R.styleable.CustomeRectView_rectWidth,200); break; } } array.recycle(); }}

@Overrideprotected void onDraw(Canvas canvas) { super.onDraw(canvas); mPiant=new Paint(); mPiant.setColor(rectColor);//设置画笔的颜色 mPiant.setStyle(Paint.Style.FILL);//设置画笔的样式 mPiant.setAntiAlias(true);//去除锯齿 /** * Draw the specified Rect using the specified paint. The rectangle will * be filled or framed based on the Style in the paint. * * @param left The left side of the rectangle to be drawn * @param top The top side of the rectangle to be drawn * @param right The right side of the rectangle to be drawn * @param bottom The bottom side of the rectangle to be drawn * @param paint The paint used to draw the rect */ canvas.drawRect(0,0,getWidth(),getHeight(),mPiant);}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec);}

@Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); int widthMode=MeasureSpec.getMode(widthMeasureSpec); int widthSize=MeasureSpec.getSize(widthMeasureSpec); int heightMode=MeasureSpec.getMode(heightMeasureSpec); int heightSize=MeasureSpec.getSize(heightMeasureSpec); int width; int height; //如果设置了明确的大小 if(widthMode==MeasureSpec.EXACTLY){ width=widthSize; }else{ //设置宽 width=dpToPx(getContext(),200); } if(heightMode==MeasureSpec.EXACTLY){ height=heightSize; }else{ //设置高 height=dpToPx(getContext(),200); } setMeasuredDimension(width,height); } /** * 根据手机的分辨率从 dp 的单位 转成为 px(像素) */ public int dpToPx(Context context, float dpValue){ final float scale=context.getResources().getDisplayMetrics().density; return (int)(dpValue*scale+0.5f); }