Android中如何实现画图(android,开发技术)

importjava.io.InputStream;

importandroid.app.Activity;

importandroid.content.Context;

importandroid.graphics.Bitmap;

importandroid.graphics.BitmapFactory;

importandroid.graphics.Canvas;

importandroid.graphics.Color;

importandroid.graphics.LinearGradient;

importandroid.graphics.Paint;

importandroid.graphics.PorterDuff;

importandroid.graphics.PorterDuffXfermode;

importandroid.graphics.Shader;

importandroid.graphics.Typeface;

importandroid.os.Bundle;

importandroid.view.View;

publicclassAlphaBitmapextendsActivity{

@Override

protectedvoidonCreate(BundlesavedInstanceState){

super.onCreate(savedInstanceState);

setContentView(newSampleView(this));

}

privatestaticclassSampleViewextendsView{

privateBitmapmBitmap;

privateBitmapmBitmap2;

privateBitmapmBitmap3;

privateShadermShader;

privatestaticvoiddrawIntoBitmap(Bitmapbm){

floatx=bm.getWidth();

floaty=bm.getHeight();

//建一个有制定对象的画布

Canvasc=newCanvas(bm);

Paintp=newPaint();

//主要用来消除边缘吧从效果上看好像false的话有毛边

p.setAntiAlias(true);

p.setAlpha(0x555555);//灰色

c.drawCircle(x/2,y/2,x/2,p);

p.setAlpha(0x0000ff);//蓝色

p.setXfermode(newPorterDuffXfermode(PorterDuff.Mode.SRC_OVER));

//下面是字体的相关设置

p.setTextSize(20);

StringfamilyName="宋体";

Typefacefont=Typeface.create(familyName,Typeface.ITALIC);

p.setTypeface(font);

p.setTextAlign(Paint.Align.CENTER);

Paint.FontMetricsfm=p.getFontMetrics();

c.drawText("我爱android",x/2,(y-fm.ascent)/2,p);

}

publicSampleView(Contextcontext){

super(context);

setFocusable(true);

//得到图像的几种方法

InputStreamis=context.getResources().
openRawResource(R.drawable.app_sample_code);

mBitmap=BitmapFactory.decodeStream(is);

//从一幅图像抽取色值变为新的图像，一般是画笔的颜色同下面
p.setColor(Color.BLUE);

mBitmapmBitmap2=mBitmap.extractAlpha();

mBitmap3=Bitmap.createBitmap(200,200,Bitmap.Config.ALPHA_8);

drawIntoBitmap(mBitmap3);

//一种渐变效果

mShader=newLinearGradient(0,0,150,70,newint[]{

Color.RED,Color.GREEN,Color.BLUE},

null,Shader.TileMode.MIRROR);

}

@OverrideprotectedvoidonDraw(Canvascanvas){

canvas.drawColor(Color.LTGRAY);

Paintp=newPaint();

floaty=10;

p.setColor(Color.BLUE);

canvas.drawBitmap(mBitmap,10,y,p);

y+=mBitmap.getHeight()+10;

canvas.drawBitmap(mBitmap2,10,y,p);

y+=mBitmap2.getHeight()+10;

p.setShader(mShader);

canvas.drawBitmap(mBitmap3,10,y,p);

}

}

}