Android编程基于自定义view实现公章效果示例【附源码下载】

public void addArc(RectF oval, float startAngle, float sweepAngle) {
 addArc(oval.left, oval.top, oval.right, oval.bottom, startAngle, sweepAngle);
}

path.addArc(oval,-(firstrad-textPadding*i/2), textPadding);

<declare-styleable name="Seal">
 <attr name="scale_text_size" format="dimension" />
 <attr name="scale_text_color" format="color" />
 <attr name="scale_text" format="string" />
 <attr name="scale_text_padding" format="float" />
 <attr name="circle_stroke_width" format="dimension" />
 <attr name="circle_color" format="color" />
 <attr name="circle_radius" format="dimension" />
</declare-styleable>

private void initViews(AttributeSet attrs, int defStyle) {
 TypedArray typedArray = getContext().obtainStyledAttributes(attrs, R.styleable.Seal, defStyle, 0);
 circleText = typedArray.getString(R.styleable.Seal_scale_text);
 textSize = typedArray.getDimension(R.styleable.Seal_scale_text_size, 20);
 scaleTextColor = typedArray.getColor(R.styleable.Seal_scale_text_color, getResources().getColor(R.color.c9));
 textPadding=typedArray.getFloat(R.styleable.Seal_scale_text_padding,50);
 circleStrokeWidth = typedArray.getDimensionPixelSize(R.styleable.Seal_circle_stroke_width, 3);
 circleColor = typedArray.getColor(R.styleable.Seal_circle_color, getResources().getColor(R.color.c9));
 circleRadius = typedArray.getDimensionPixelSize(R.styleable.Seal_circle_radius, 7);
 typedArray.recycle();
}

@Override
protected void onDraw(Canvas rootCanvas) {
 super.onDraw(rootCanvas);
 Bitmap image = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
 Canvas canvas = new Canvas(image);
 Paint paint=new Paint();
 drawRing(canvas,paint);
 drawStar(canvas);
 drawText(canvas);
 rootCanvas.drawBitmap(image, 0, 0, null);
}

//圆环
private void drawRing(Canvas canvas, Paint paint) {
 centre = canvas.getWidth() / 2; // 获取圆心的x坐标
 radius = (int) (centre - circleStrokeWidth / 2); // 圆环的半径
 paint.setColor(Color.RED); // 设置圆环的颜色
 paint.setStyle(Paint.Style.STROKE); // 设置空心
 paint.setStrokeWidth(circleStrokeWidth); // 设置圆环的宽度
 paint.setAntiAlias(true); // 消除锯齿
 canvas.drawCircle(centre, centre, radius, paint); // 画出圆环
}
//绘制五角星
private void drawStar(Canvas canvas){
 float start_radius = (float) ((radius / 2)*1.1);
 int x = centre, y = centre;
 float x1,y1,x2,y2,x3,y3,x4,y4,x5,y5;
 float r72 = (float) Math.toRadians(72);
 float r36 = (float) Math.toRadians(36);
 //顶点
 x1 = x;
 y1 = y - start_radius;
 //左1
 x2 = (float) (x - start_radius*Math.sin(r72));
 y2 = (float) (y - start_radius*Math.cos(r72));
 //右1
 x3 = (float) (x + start_radius*Math.sin(r72));
 y3 = (float) (y - start_radius*Math.cos(r72));
 //左2
 x4 = (float) (x - start_radius*Math.sin(r36));
 y4 = (float) (y + start_radius*Math.cos(r36));
 //右2
 x5 = (float) (x + start_radius*Math.sin(r36));
 y5 = (float) (y + start_radius*Math.cos(r36));
 //连接各个节点，绘制五角星
 Path path = new Path();
 path.moveTo(x1, y1);
 path.lineTo(x5, y5);
 path.lineTo(x2, y2);
 path.lineTo(x3, y3);
 path.lineTo(x4, y4);
 path.close();
 Paint paint = new Paint();
 paint.setColor(Color.RED);
 canvas.drawPath(path, paint);
}
//文字
private void drawText(Canvas canvas){
 Paint paint = new Paint();
 paint.setColor(Color.RED);
 paint.setTypeface(Typeface.DEFAULT_BOLD);
 paint.setTextAlign(Paint.Align.CENTER);
 paint.setTextSize(radius/5+5);
 //圆弧文字所在矩形范围
 RectF oval=new RectF(0, 0, 2*radius, (float) (2*radius));
 //第一个文字偏移角度，其中padding/2为文字间距
 float firstrad = 90 + textPadding * (circleText.length()) / 4 - textPadding/8;
 for(int i = 0; i < circleText.length(); i++){
  Path path = new Path();
  //根据角度生成弧线路径
  path.addArc(oval,-(firstrad-textPadding*i/2), textPadding);
  canvas.drawTextOnPath(String.valueOf(circleText.charAt(i)), path, -(float) (radius/3),(float) (radius/3), paint);
 }
}

<com.xzh.sealmaster.view.SealView
 android:layout_width="200dp"
 android:layout_height="200dp"
 android:layout_gravity="center"
 app:scale_text_size="16sp"
 app:scale_text_padding="50"
 app:scale_text="华为上海有限公司"
 />