canvas drawBitmap demo

介绍

MainActivity

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private Button mBtn_reset,mBtn_left,mBtn_right,mBtnzoomin,mBtnzoomout;
private MyView myView;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bindViews();//init button so on
}

private void bindViews(){
mBtn_reset = (Button) findViewById(R.id.btn_reset);
mBtn_left = (Button) findViewById(R.id.btn_left);
mBtn_right = (Button) findViewById(R.id.btn_right);
mBtnzoomin = (Button) findViewById(R.id.btn_zoomin);
mBtnzoomout = (Button) findViewById(R.id.btn_zoomout);

myView = (MyView) findViewById(R.id.myView);
//        myView = new MyView(this);

mBtn_reset.setOnClickListener(this);
mBtn_left.setOnClickListener(this);
mBtn_right.setOnClickListener(this);
mBtnzoomin.setOnClickListener(this);
mBtnzoomout.setOnClickListener(this);

}
@Override
public void onClick(View view) {
switch (view.getId()){
case R.id.btn_reset:
myView.setMethod(0);
break;
case R.id.btn_left:
myView.setMethod(1);
break;
case R.id.btn_right:
myView.setMethod(2);
break;
case R.id.btn_zoomin:
myView.setMethod(3);
break;
case R.id.btn_zoomout:
myView.setMethod(4);
break;
default:
Log.i(this.getClass().getSimpleName(),"switch default");

}
}
}

MyView

public class MyView extends View {
private final String TAG = "MyView";
private Bitmap mBitmap;
private Matrix matrix =  new Matrix();
private float sx = 0.0f;//倾斜度
private int mWidth,mHeight;//位宽高
private float mScale = 1.0f;//缩放比例
private int method = 0;

public MyView(Context context) {
this(context, null);
}

public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}

public MyView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}

private void init() {
Log.e(TAG, "init");
mBitmap = BitmapFactory.decodeResource(getResources(), R.raw.img_meizi);
mWidth = mBitmap.getWidth();
mHeight = mBitmap.getHeight();
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);

switch(method){
case 0:
matrix.reset();
resetValue();
break;
case 1:
sx += 0.1;
matrix.setSkew(sx,0);
break;
case 2:
sx -= 0.1;
matrix.setSkew(sx,0);
break;
case 3:
if(mScale < 2.0){
mScale += 0.1;
}
matrix.setScale(mScale,mScale);
break;
case 4:
if(mScale > 0.5){
mScale -= 0.1;
}
matrix.setScale(mScale,mScale);
break;
default:
Log.i(this.getClass().getSimpleName(),"switch default");
}
//根据原始位图创新新图片
Bitmap bitmap = Bitmap.createBitmap(mBitmap,0,0, mWidth, mHeight, matrix,true);
canvas.drawBitmap(bitmap, matrix,null);//绘制新图
}

private void resetValue() {
mScale = 1.0f;
sx = 0.0f;
}

public void setMethod(int i){
method = i;
postInvalidate();
}
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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">

<LinearLayout
android:id="@+id/ly_bar"
android:layout_width="match_parent"
android:layout_height="64dp"
android:layout_alignParentBottom="true">
<Button
android:id="@+id/btn_reset"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:text="重置" />

<Button
android:id="@+id/btn_left"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:text="左倾" />

<Button
android:id="@+id/btn_right"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:text="右倾" />

<Button
android:id="@+id/btn_zoomin"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:text="放大" />

<Button
android:id="@+id/btn_zoomout"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:text="缩小" />
</LinearLayout>

<com.kang.test.view.MyView
android:id="@+id/myView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="@id/ly_bar"/>

</RelativeLayout>