Android 自定义view，画图板练习(2)

代码中，重要地方都有注解

布局代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <android.support.v7.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_margin="15dp"
        android:layout_weight="1"
        app:cardElevation="4dp"
        app:cardUseCompatPadding="true">
        <com.example.gcc.okhttpl.richeditor.PaintView
            android:id="@+id/activity_paint_pv"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </android.support.v7.widget.CardView>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:gravity="center_vertical"
        android:orientation="horizontal">
        <TextView
            android:id="@+id/activity_paint_undo"
            style="@style/paint_menu_text_view_style"
            android:text="撤销" />
        <TextView
            android:id="@+id/activity_paint_redo"
            style="@style/paint_menu_text_view_style"
            android:text="恢复" />
        <TextView
            android:id="@+id/activity_paint_color"
            style="@style/paint_menu_text_view_style"
            android:text="红色" />
        <TextView
            android:id="@+id/activity_paint_clear"
            style="@style/paint_menu_text_view_style"
            android:text="清空" />
        <TextView
            android:id="@+id/activity_paint_eraser"
            style="@style/paint_menu_text_view_style"
            android:text="橡皮擦" />
        <TextView
            android:id="@+id/activity_paint_save"
            style="@style/paint_menu_text_view_style"
            android:text="保存" />
    </LinearLayout>
</LinearLayout>

Activity代码

public class PaintViewActivity extends AppCompatActivity {
    private PaintView paintView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_paint_view);
        initView();
        initMenu();
    }
    /**
     * 初始化
     */
    private void initView() {
        paintView = (PaintView) findViewById(R.id.activity_paint_pv);
    }
    /**
     * 初始化底部菜单
     */
    private void initMenu() {
        //撤销
        menuItemSelected(R.id.activity_paint_undo, new MenuSelectedListener() {
            @Override
            public void onMenuSelected() {
                ToastUtils.show(PaintViewActivity.this, "撤销");
                paintView.undo();
            }
        });
        //恢复
        menuItemSelected(R.id.activity_paint_redo, new MenuSelectedListener() {
            @Override
            public void onMenuSelected() {
                ToastUtils.show(PaintViewActivity.this, "恢复");
                paintView.redo();
            }
        });
        //颜色
        menuItemSelected(R.id.activity_paint_color, new MenuSelectedListener() {
            @Override
            public void onMenuSelected() {
                ToastUtils.show(PaintViewActivity.this, "红色");
                paintView.setPaintColor(Color.RED);
            }
        });
        //清空
        menuItemSelected(R.id.activity_paint_clear, new MenuSelectedListener() {
            @Override
            public void onMenuSelected() {
                ToastUtils.show(PaintViewActivity.this, "清空");
                paintView.clearAll();
            }
        });
        //橡皮擦
        menuItemSelected(R.id.activity_paint_eraser, new MenuSelectedListener() {
            @Override
            public void onMenuSelected() {
                ToastUtils.show(PaintViewActivity.this, "橡皮擦");
                paintView.setEraserModel(true);
            }
        });
        //保存
        menuItemSelected(R.id.activity_paint_save, new MenuSelectedListener() {
            @Override
            public void onMenuSelected() {
                String path = Environment.getExternalStorageDirectory().getPath()
                        + File.separator + Strings.FILE_PATH + File.separator + Strings.CACHE_PATH;
                String imgName = "paint.jpg";
                if (paintView.saveImg(path,imgName)) {
                    ToastUtils.show(PaintViewActivity.this, "保存成功");
                }
            }
        });
    }
    /**
     * 选中底部 Menu 菜单项
     */
    private void menuItemSelected(int viewId, final MenuSelectedListener listener) {
        findViewById(viewId).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                listener.onMenuSelected();
            }
        });
    }
    @Override
    protected void onDestroy() {
        super.onDestroy();
        ToastUtils.cancel();
    }
    interface MenuSelectedListener {
        void onMenuSelected();
    }
}

这是橡皮擦使用PorterDuffXfermode踩坑模式

简单设置PaintView代码：

1. 首先把硬件加速打开,也就是把init()方法里，下面行代码注释掉：
  //setBackgroundColor(Color.WHITE);
  //setLayerType(View.LAYER_TYPE_SOFTWARE, null);
2.修改橡皮擦颜色
 eraserPaint.setColor(Color.WHITE);
 //eraserPaint.setColor(Color.TRANSPARENT);
 //eraserPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));

这种模式即不会导致过分绘制，也不会有软件加速的坑，但前提是绘图板背景色彩是复古的

即使在使用过渡绘制模式的状况下，暂时觉得强度也可以，在低端机上也没有明显的卡顿感，绘制轨迹蛮跟手的。个人觉得这种绘图板并不需要SurfaceView

有错误，请指出

共勉 : )

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