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本篇文章为大家展示了如何在Android应用中实现自定义View,内容简明扼要并且容易理解,绝对能使你眼前一亮,通过这篇文章的详细介绍希望你能有所收获。
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自定义view大概可以分为四个大类,主要是通过实现方式来区分
1.自绘控件,继承view,重写onDraw方法,在其中进行绘制,需要自己适配边距等等
2.继承ViewGroup派生的特殊Layout,主要用于实现自定义布局,也需要自己适配边距等
3.继承特定的View(如TextView等),不用自己适配支持wrap_conten,match_parent,可以给其加入新的功能
4.继承特定的ViewGroup,例如linearlayout,多用于多个控件的组合view,也不用自己去做适配
自绘控件
这种自定义view是最复杂的一种,因为既要适配wrap_conten,match_parent又要通过条件判断来在屏幕上绘制不同的内容,主要就是重写onDraw方法
以下是一个简单的onDraw重写代码
@Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); final int paddingLeft = getPaddingLeft(); final int paddingRight = getPaddingRight(); final int paddingTop = getPaddingTop(); final int paddingBottom = getPaddingBottom(); //get the view's width and height and decide the radiu int width = getWidth() - paddingLeft - paddingRight; int height = getHeight() - paddingTop - paddingBottom; radiu = Math.min(width , height) / 2 - boundWidth - progressWidth; //setup the paint paint.setStyle(Paint.Style.STROKE); paint.setStrokeWidth(boundWidth); paint.setColor(Color.BLACK); //draw the inner circle int centerX = paddingLeft + getWidth()/2; int centerY = paddingTop + getHeight() / 2; canvas.drawCircle(centerX,centerY, radiu, paint); float totalRadiu = radiu +boundWidth +progressWidth/2; //draw the circlr pic if (drawable != null&&bitmap == null) { image = ((BitmapDrawable) drawable).getBitmap(); bitmap = Bitmap.createBitmap((int)(2*totalRadiu),(int)(2*totalRadiu), Bitmap.Config.ARGB_8888); Canvas bitmapCanvas = new Canvas(bitmap); Paint bitmapPaint = new Paint(); bitmapPaint.setAntiAlias(true); bitmapCanvas.drawCircle(totalRadiu, totalRadiu, radiu, bitmapPaint); bitmapPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN)); bitmapCanvas.drawBitmap(image,null,new RectF(0,0,2*totalRadiu,2*totalRadiu) , bitmapPaint); } Rect rect = new Rect((int)(centerX -totalRadiu),(int)(centerY-totalRadiu),(int)(centerX+totalRadiu),(int)(centerY+ totalRadiu)); canvas.save(); if(isRotate) canvas.rotate(rotateDegree,centerX,centerY); canvas.drawBitmap(bitmap,null ,rect, paint); canvas.restore(); //set paint for arc paint.setStrokeWidth(progressWidth); paint.setStrokeCap(Paint.Cap.ROUND); //prepare for draw arc RectF oval = new RectF(); oval.left = centerX -totalRadiu ; oval.top =centerY- totalRadiu ; oval.right = centerX + totalRadiu; oval.bottom = centerY+ totalRadiu; paint.setColor(progressBackColor); //draw background arc canvas.drawArc(oval, arcStar, arcEnd, false, paint); //draw progress arc paint.setColor(progressColor); canvas.drawArc(oval, arcStar, progress, false, paint); }