上次去一个公司面试,面试官问了一个题,怎么用android的自定义view实现一个公章的效果,据说这是华为之前的面试题,我想了下,要是公章的效果,最外层是一个圆,里面是一个五角星,但是这文字怎么画呢,比较难搞,后来回来看了下java的api,发现人家的Path里面本来就提供了这么一个方法:
public void addArc(RectF oval, float startAngle, float sweepAngle) { addArc(oval.left, oval.top, oval.right, oval.bottom, startAngle, sweepAngle); }然后人家解释说了,根据狐线的角度生成相应的路径,所以我们就可以给文字设置一个相应绘制区域,使其绘制的文字都在这个区域内,
path.addArc(oval,-(firstrad-textPadding*i/2), textPadding);
接下来我们只需要在这个区域内把文字绘制上去就行了。
好的,下面是全部代码:
首先继承自View,我们在构造里面初始化,同样为了方便程序的扩展性,我们用自定义属性,
然后我们初始化的时候主要初始化文字,文字大小,文字间距,文字颜色等等,
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);
}
接下来是对应的三个方法:画圆环(ring),五角星(star),文字(text)
//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);
}
}
有需要源码的,请到下面地址下载:http://download.csdn.net/detail/xiangzhihong8/9479372好的,就是这么简单,有任何疑问的请加我们的技术群278792776或者188716429