对于安卓程序员来说，自定义view简直不要太重要，毕竟有很多功能，譬如圆形头像这些，用单纯的原生非常难以实现，而用自定义view，简直分分钟
效果视频
分析
起始角度
如下图所示，起点角度为150，终点角度为240
圆弧
白色圆弧为整个圆弧范围，蓝色圆弧为根据数据变动而覆盖白色圆弧，蓝色圆弧比白色圆弧大一点，突出显示
InnerArcPaint.setStrokeWidth( Width * (float)0.1 ); OuterArcPaint.setStrokeWidth( Width * (float)0.12 );
指针
中间的水滴指针是一个白色的水滴图片，下图蓝色为选择文件的背景颜色（截图），由于水滴指向-135度，将图像旋转-75度，水滴尖刚好指向150度的起点。
代码
初始化属性
private void InitPaint(){ InnerArcPaint = new Paint( ); InnerArcPaint.setColor( Color.WHITE ); InnerArcPaint.setAntiAlias( true ); InnerArcPaint.setStyle( Paint.Style.STROKE ); OuterArcPaint = new Paint( ); OuterArcPaint.setColor( Color.BLUE ); OuterArcPaint.setAntiAlias( true ); OuterArcPaint.setStyle( Paint.Style.STROKE ); OuterArcPaint.setShadowLayer( (float)10,(float)10,(float)10,Color.parseColor( "#99000000" ) ); TextPaint = new Paint( ); TextPaint.setColor( Color.RED ); TextPaint.setStyle( Paint.Style.STROKE ); TextPaint.setTextSize( 60 ); TextPaint.setStrokeWidth( 2 ); ScalePaint = new Paint( ); ScalePaint.setColor( Color.WHITE ); ScalePaint.setTextSize( 25 ); //硬件加速 setLayerType( LAYER_TYPE_SOFTWARE,null ); } 画布
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure( widthMeasureSpec, heightMeasureSpec ); int Width = MeasureSpec.getSize( widthMeasureSpec ); InnerArcPaint.setStrokeWidth( Width * (float)0.1 ); OuterArcPaint.setStrokeWidth( Width * (float)0.12 ); oval = new RectF( ); oval.left = Width * (float)0.2; oval.top = Width * (float)0.2; oval.right = Width * (float)0.8; oval.bottom = Width * (float)0.8; //宽、高一致，使画布无论边长如何变化，都成为一个正方形 setMeasuredDimension( Width,Width ); } 绘制内圆弧
//绘制内圆弧 private void DrawInnerArc(Canvas canvas){ //保存之前的画布 canvas.save(); canvas.drawArc( oval, StartAngle,SweepAngle,false,InnerArcPaint); } 绘制外圆弧
//绘制外圆弧 private void DrawOuterArc(Canvas canvas){ canvas.save(); canvas.drawArc( oval, StartAngle,SweepAngle * CurrentData / 300,false,OuterArcPaint); } 绘制中间指针
//绘制中间指针 private void DrawArrow(Canvas canvas){ canvas.save(); Bitmap bitmap = BitmapFactory.decodeResource( getResources(),R.mipmap.waterdrop ); int width = 75; int height = 75; int NewWidth = (int)(getWidth() * 0.08); float ScaleWidth = (float) (NewWidth / width); float ScaleHeight = (float) (NewWidth / height); Matrix matrix = new Matrix( ); //顺序不能颠倒 matrix.setRotate( -75 + (SweepAngle * CurrentData / 300),bitmap.getWidth()/2,bitmap.getHeight()/2 ); matrix.postScale( ScaleWidth,ScaleHeight ); Bitmap bitmap1 = Bitmap.createBitmap( bitmap,0,0,width,height,matrix,true ); canvas.drawBitmap( bitmap1,getWidth()/2 - bitmap1.getWidth()/2,getHeight()/2 - bitmap1.getHeight()/2,InnerArcPaint ); bitmap.recycle(); bitmap1.recycle(); } 绘制中间文字
private void DrawCurrentDataText(Canvas canvas){ canvas.save(); Rect rect = new Rect( ); String str = String.valueOf( CurrentData ) + "KG"; TextPaint.setColor( Color.RED ); TextPaint.getTextBounds( str,0,str.length(),rect ); canvas.drawText( str,getWidth()/2 - rect.width()/2,(int)(getHeight() * (float)0.38),TextPaint ); } 绘制左右两边文字
private void DrawScaleRightText(Canvas canvas){ canvas.save(); Rect rect = new Rect( ); String str = "300KG"; TextPaint.setTextSize( 45 ); TextPaint.getTextBounds( str,0,str.length(),rect ); TextPaint.setColor( Color.WHITE ); canvas.drawText( str,getWidth()-getWidth()/6,(getHeight()/2+getWidth()/5) ,TextPaint ); } private void DrawScaleLeftText(Canvas canvas){ canvas.save(); Rect rect = new Rect( ); String str = "0KG"; TextPaint.setTextSize( 45 ); TextPaint.getTextBounds( str,0,str.length(),rect ); TextPaint.setColor( Color.WHITE ); canvas.drawText( str,(getWidth()/2-(getWidth()/3 + 75)),(getHeight()/2+getWidth()/5) ,TextPaint ); } 动画
public void SetCurrentData(final float data, TimeInterpolator interpolator){ long time = ( (long)Math.abs( data- CurrentData ) *20); final ValueAnimator valueAnimator = ValueAnimator.ofFloat( CurrentData,data ).setDuration( time ); valueAnimator.setInterpolator( interpolator ); valueAnimator.addUpdateListener( new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { CustomView_ClockDial.this.CurrentData = (float)valueAnimator.getAnimatedValue(); invalidate(); } } ); valueAnimator.start(); } 全部代码
public class CustomView_ClockDial extends View { //内圆弧画笔 private Paint InnerArcPaint; //外圆弧画笔 private Paint OuterArcPaint; //文字画笔 private Paint TextPaint; //刻度画笔 private Paint ScalePaint; //圆弧范围 private RectF oval; //当前数据 private float CurrentData = 0; //起点角度 private float StartAngle = 150; //终点角度 private float SweepAngle = 240; public CustomView_ClockDial(Context context) { super( context ); InitPaint(); } public CustomView_ClockDial(Context context, @Nullable AttributeSet attrs) { super( context, attrs ); InitPaint(); } public CustomView_ClockDial(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super( context, attrs, defStyleAttr ); InitPaint(); } private void InitPaint(){ InnerArcPaint = new Paint( ); InnerArcPaint.setColor( Color.WHITE ); InnerArcPaint.setAntiAlias( true ); InnerArcPaint.setStyle( Paint.Style.STROKE ); OuterArcPaint = new Paint( ); OuterArcPaint.setColor( Color.BLUE ); OuterArcPaint.setAntiAlias( true ); OuterArcPaint.setStyle( Paint.Style.STROKE ); OuterArcPaint.setShadowLayer( (float)10,(float)10,(float)10,Color.parseColor( "#99000000" ) ); TextPaint = new Paint( ); TextPaint.setColor( Color.RED ); TextPaint.setStyle( Paint.Style.STROKE ); TextPaint.setTextSize( 60 ); TextPaint.setStrokeWidth( 2 ); ScalePaint = new Paint( ); ScalePaint.setColor( Color.WHITE ); ScalePaint.setTextSize( 25 ); //硬件加速 setLayerType( LAYER_TYPE_SOFTWARE,null ); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure( widthMeasureSpec, heightMeasureSpec ); int Width = MeasureSpec.getSize( widthMeasureSpec ); InnerArcPaint.setStrokeWidth( Width * (float)0.1 ); OuterArcPaint.setStrokeWidth( Width * (float)0.12 ); oval = new RectF( ); oval.left = Width * (float)0.2; oval.top = Width * (float)0.2; oval.right = Width * (float)0.8; oval.bottom = Width * (float)0.8; //宽、高一致，使画布无论边长如何变化，都成为一个正方形 setMeasuredDimension( Width,Width ); } @Override protected void onDraw(Canvas canvas) { super.onDraw( canvas ); DrawInnerArc(canvas); DrawOuterArc(canvas); DrawArrow(canvas); DrawCurrentDataText(canvas); DrawScaleRightText(canvas); DrawScaleLeftText(canvas); } //绘制内圆弧 private void DrawInnerArc(Canvas canvas){ //保存之前的画布 canvas.save(); canvas.drawArc( oval, StartAngle,SweepAngle,false,InnerArcPaint); } //绘制外圆弧 private void DrawOuterArc(Canvas canvas){ canvas.save(); canvas.drawArc( oval, StartAngle,SweepAngle * CurrentData / 300,false,OuterArcPaint); } //绘制中间指针 private void DrawArrow(Canvas canvas){ canvas.save(); Bitmap bitmap = BitmapFactory.decodeResource( getResources(),R.mipmap.waterdrop ); int width = 75; int height = 75; int NewWidth = (int)(getWidth() * 0.08); float ScaleWidth = (float) (NewWidth / width); float ScaleHeight = (float) (NewWidth / height); Matrix matrix = new Matrix( ); //顺序不能颠倒 matrix.setRotate( -75 + (SweepAngle * CurrentData / 300),bitmap.getWidth()/2,bitmap.getHeight()/2 ); matrix.postScale( ScaleWidth,ScaleHeight ); Bitmap bitmap1 = Bitmap.createBitmap( bitmap,0,0,width,height,matrix,true ); canvas.drawBitmap( bitmap1,getWidth()/2 - bitmap1.getWidth()/2,getHeight()/2 - bitmap1.getHeight()/2,InnerArcPaint ); bitmap.recycle(); bitmap1.recycle(); } private void DrawCurrentDataText(Canvas canvas){ canvas.save(); Rect rect = new Rect( ); String str = String.valueOf( CurrentData ) + "KG"; TextPaint.setColor( Color.RED ); TextPaint.getTextBounds( str,0,str.length(),rect ); canvas.drawText( str,getWidth()/2 - rect.width()/2,(int)(getHeight() * (float)0.38),TextPaint ); } private void DrawScaleRightText(Canvas canvas){ canvas.save(); Rect rect = new Rect( ); String str = "300KG"; TextPaint.setTextSize( 45 ); TextPaint.getTextBounds( str,0,str.length(),rect ); TextPaint.setColor( Color.WHITE ); canvas.drawText( str,getWidth()-getWidth()/6,(getHeight()/2+getWidth()/5) ,TextPaint ); } private void DrawScaleLeftText(Canvas canvas){ canvas.save(); Rect rect = new Rect( ); String str = "0KG"; TextPaint.setTextSize( 45 ); TextPaint.getTextBounds( str,0,str.length(),rect ); TextPaint.setColor( Color.WHITE ); canvas.drawText( str,(getWidth()/2-(getWidth()/3 + 75)),(getHeight()/2+getWidth()/5) ,TextPaint ); } public void SetCurrentData(final float data, TimeInterpolator interpolator){ long time = ( (long)Math.abs( data- CurrentData ) *20); final ValueAnimator valueAnimator = ValueAnimator.ofFloat( CurrentData,data ).setDuration( time ); valueAnimator.setInterpolator( interpolator ); valueAnimator.addUpdateListener( new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { CustomView_ClockDial.this.CurrentData = (float)valueAnimator.getAnimatedValue(); invalidate(); } } ); valueAnimator.start(); } } 下载链接
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