android前台渲染圖片，

android前台渲染圖片，

android前台渲染，主要是重寫view的ondraw方法，在canvas裡操作

自訂MyView類

package com.ssln;import android.annotation.SuppressLint;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Matrix;import android.graphics.Paint;import android.util.AttributeSet;import android.view.View;public class MyView extends View {    private Bitmap bitmap;        //圖片    private Paint paint;        //畫筆    public MyView(Context context, AttributeSet attrs) {        super(context, attrs);        initBitmap();    }    /**     * 初始化資訊     */    public void initBitmap()    {        //執行個體化畫筆         paint=new Paint();                  //從資源中載入         bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.img);    }    @SuppressLint("DrawAllocation")    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        paint.setAntiAlias(true);        //開啟消除鋸齒        paint.setColor(Color.BLACK);    //設定畫筆顏色        paint.setTextScaleX(15);        //設定文字大小        canvas.drawBitmap(bitmap, 10,10, paint); //在10x10的位置畫圖片        canvas.save();                    //儲存畫布狀態                Matrix m1=new Matrix();            //矩陣        m1.setTranslate(500, 10);        //平移 X500 Y10        Matrix m2=new Matrix();            m2.setRotate(15);                //旋轉15°        Matrix m3=new Matrix();                    m3.setConcat(m1, m2);            //合并矩陣        m1.setScale(0.8f, 0.8f);        //設定縮放比例        m2.setConcat(m3, m1);            //合并        canvas.drawBitmap(bitmap, m2, paint);  //畫圖，經過了平移，旋轉，縮放        canvas.restore();                //恢複畫布狀態        canvas.save();        paint.setAlpha(180);            //設定透明度        m1.setTranslate(200, 100);        m2.setScale(1.3f, 1.3f);        m3.setConcat(m1, m2);        canvas.drawBitmap(bitmap, m3, paint);  //畫圖，經過了平移，縮放        paint.reset();                  //重設畫筆        canvas.restore();        paint.setTextSize(24);        paint.setColor(Color.BLACK);        canvas.drawText("圖片寬度:"+bitmap.getWidth(), 20,240, paint); //寫文字，映像的寬度        canvas.drawText("圖片高度:"+bitmap.getHeight(), 20,270, paint);        paint.reset();        } }

 

修改activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.ssln.MainActivity" >    <com.ssln.MyView        android:layout_width="fill_parent"        android:layout_height="fill_parent"         /></RelativeLayout>

 運行效果如下