Android的绘图继承于View组件，重写onDraw(Canvas canvas) 方法时涉及一个绘图API: Canvas 代表了依附于指定View的画布，并且提供了很多绘制方法。
Canvas提供的方法还涉及一个API: Paint ,Paint代表了Canvas上的画笔，主要用于设置绘制风格，画笔颜色，粗细，填充风格等。
Path代表任意多条直线连接而成的任意图形，当Canvas根据Path绘制图形时，它可以绘制出任意形状的图形。
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import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.LinearGradient;import android.graphics.Paint;import android.graphics.Path;import android.graphics.RectF;import android.graphics.Shader;import android.util.AttributeSet;import android.view.View;public class MyView extends View { public MyView(Context context, AttributeSet set) { super(context, set); } @Override // 重写该方法，进行绘图 protected void onDraw(Canvas canvas) { super.onDraw(canvas); // 把整张画布绘制成白色 canvas.drawColor(Color.WHITE); Paint paint = new Paint(); // 去锯齿 paint.setAntiAlias(true); paint.setColor(Color.BLUE); paint.setStyle(Paint.Style.STROKE); paint.setStrokeWidth(3); // 绘制圆形 canvas.drawCircle(40, 40, 30, paint); // 绘制正方形 canvas.drawRect(10, 80, 70, 140, paint); // 绘制矩形 canvas.drawRect(10, 150, 70, 190, paint); RectF re1 = new RectF(10, 200, 70, 230); // 绘制圆角矩形 canvas.drawRoundRect(re1, 15, 15, paint); RectF re11 = new RectF(10, 240, 70, 270); // 绘制椭圆 canvas.drawOval(re11, paint); // 定义一个Path对象，封闭成一个三角形。 Path path1 = new Path(); path1.moveTo(10, 340); path1.lineTo(70, 340); path1.lineTo(40, 290); path1.close(); // 根据Path进行绘制，绘制三角形 canvas.drawPath(path1, paint); // 定义一个Path对象，封闭成一个五角形。 Path path2 = new Path(); path2.moveTo(26, 360); path2.lineTo(54, 360); path2.lineTo(70, 392); path2.lineTo(40, 420); path2.lineTo(10, 392); path2.close(); // 根据Path进行绘制，绘制五角形 canvas.drawPath(path2, paint); // ----------设置填充风格后绘制---------- paint.setStyle(Paint.Style.FILL); paint.setColor(Color.RED); canvas.drawCircle(120, 40, 30, paint); // 绘制正方形 canvas.drawRect(90, 80, 150, 140, paint); // 绘制矩形 canvas.drawRect(90, 150, 150, 190, paint); RectF re2 = new RectF(90, 200, 150, 230); // 绘制圆角矩形 canvas.drawRoundRect(re2, 15, 15, paint); RectF re21 = new RectF(90, 240, 150, 270); // 绘制椭圆 canvas.drawOval(re21, paint); Path path3 = new Path(); path3.moveTo(90, 340); path3.lineTo(150, 340); path3.lineTo(120, 290); path3.close(); // 绘制三角形 canvas.drawPath(path3, paint); Path path4 = new Path(); path4.moveTo(106, 360); path4.lineTo(134, 360); path4.lineTo(150, 392); path4.lineTo(120, 420); path4.lineTo(90, 392); path4.close(); // 绘制五角形 canvas.drawPath(path4, paint); // ----------设置渐变器后绘制---------- // 为Paint设置渐变器 Shader mShader = new LinearGradient(0, 0, 40, 60, new int[] { Color.RED, Color.GREEN, Color.BLUE, Color.YELLOW }, null, Shader.TileMode.REPEAT); paint.setShader(mShader); // 设置阴影 paint.setShadowLayer(45, 10, 10, Color.GRAY); // 绘制圆形 canvas.drawCircle(200, 40, 30, paint); // 绘制正方形 canvas.drawRect(170, 80, 230, 140, paint); // 绘制矩形 canvas.drawRect(170, 150, 230, 190, paint); RectF re3 = new RectF(170, 200, 230, 230); // 绘制圆角矩形 canvas.drawRoundRect(re3, 15, 15, paint); RectF re31 = new RectF(170, 240, 230, 270); // 绘制椭圆 canvas.drawOval(re31, paint); Path path5 = new Path(); path5.moveTo(170, 340); path5.lineTo(230, 340); path5.lineTo(200, 290); path5.close(); // 根据Path进行绘制，绘制三角形 canvas.drawPath(path5, paint); Path path6 = new Path(); path6.moveTo(186, 360); path6.lineTo(214, 360); path6.lineTo(230, 392); path6.lineTo(200, 420); path6.lineTo(170, 392); path6.close(); // 根据Path进行绘制，绘制五角形 canvas.drawPath(path6, paint); // ----------设置字符大小后绘制---------- paint.setTextSize(24); paint.setShader(null); // 绘制7个字符串 canvas.drawText(getResources().getString(R.string.circle), 240, 50,paint); canvas.drawText(getResources().getString(R.string.square), 240, 120,paint); canvas.drawText(getResources().getString(R.string.rect), 240, 175,paint); canvas.drawText(getResources().getString(R.string.round_rect), 230,220, paint); canvas.drawText(getResources().getString(R.string.oval), 240, 260,paint); canvas.drawText(getResources().getString(R.string.triangle), 240, 325,paint); canvas.drawText(getResources().getString(R.string.pentagon), 240, 390,paint); }} |
