Canvas的剪裁功能 - wp7 开发学习之 ScrollViewer小使...- 图片拖动成效

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▪Canvas的剪裁功能 Canvas的裁剪功能 Canvas提供了ClipPath, ClipRect, ClipRegion 等方法来裁剪，通过Path, Rect ,Region 的不同组合，Android几乎可以支持任意现状的裁剪区域。 android.graphics包中定义了Point, Rect, Path, .........

▪ wp7 开发学习之 ScrollViewer小使用 wp7 开发学习之 ScrollViewer小应用 xaml <ScrollViewerWidth="400"Height="500"VerticalScrollBarVisibility="Auto"HorizontalScrollBarVisibility="Auto"><ImageSource="/Image/1.jpg"Width="600"Height="800" ></Image></ScrollViewer&g.........

▪ 图片拖动成效图片拖动效果拖拽图片效果方法一： import android.app.Activity; import android.os.Bundle; import android.view.MotionEvent; import android.view.View; import android.view.View.OnTouchListene.........

[1]Canvas的剪裁功能

来源: 互联网发布时间: 2014-02-18

Canvas的裁剪功能
    Canvas提供了ClipPath, ClipRect, ClipRegion 等方法来裁剪，通过Path, Rect ,Region 的不同组合，Android几乎可以支持任意现状的裁剪区域。

    android.graphics包中定义了Point, Rect, Path, Region 这几种几何形状，Path可以为有圆弧，椭圆，二次曲线，三次曲线，线段，矩形等基本几何图形或是由这些基本几何图形组合而成，Path可以为开放或是闭合曲线。Rect提供了定义矩形的简洁方法。Region则支持通过区域的“加”，“减”，“并”，“异或”等逻辑运算由多个Region组合而成。Region.Op定义了Region支持的区域间运算种类。

    Clipping 介绍有Region运算来为Canvs定义剪裁区域后，同一幅图最后显示的效果。canvas.save();和canvas.restore();用于保存和恢复Canvas的状态属性。

    drawScene定义了绘图的内容：一条红线，一个绿圆，和“Clipping”文字。

private void drawScene(Canvas canvas) {
	canvas.clipRect(0, 0, 100, 100);
	
	canvas.drawColor(Color.WHITE);
 
	mPaint.setColor(Color.RED);
	canvas.drawLine(0, 0, 100, 100, mPaint);
 
	mPaint.setColor(Color.GREEN);
	canvas.drawCircle(30, 70, 30, mPaint);
 
	mPaint.setColor(Color.BLUE);
	canvas.drawText("Clipping", 100, 30, mPaint);
}

剪裁区域为两个矩形相减：

canvas.save();
canvas.translate(160, 10);
canvas.clipRect(10, 10, 90, 90);
canvas.clipRect(30, 30, 70, 70, Region.Op.DIFFERENCE);
drawScene(canvas);
canvas.restore();

剪裁区域为一个圆：

canvas.save();
canvas.translate(10, 160);
mPath.reset();
canvas.clipPath(mPath); // makes the clip empty
mPath.addCircle(50, 50, 50, Path.Direction.CCW);
canvas.clipPath(mPath, Region.Op.REPLACE);
drawScene(canvas);
canvas.restore();

剪裁区域为两个矩形的并集：

canvas.save();
canvas.translate(160, 160);
canvas.clipRect(0, 0, 60, 60);
canvas.clipRect(40, 40, 100, 100, Region.Op.UNION);
drawScene(canvas);
canvas.restore();

剪裁区域为两个矩形的异或集：

canvas.save();
canvas.translate(10, 310);
canvas.clipRect(0, 0, 60, 60);
canvas.clipRect(40, 40, 100, 100, Region.Op.XOR);
drawScene(canvas);
canvas.restore();

最后一个为两个矩形的逆向差集：

canvas.save();
canvas.translate(160, 310);
canvas.clipRect(0, 0, 60, 60);
canvas.clipRect(40, 40, 100, 100,
Region.Op.REVERSE_DIFFERENCE);
drawScene(canvas);
canvas.restore();

效果图片：

1 楼 lansuiyun 2012-09-13

有个地方不太明白，能不能解答一下。
Region.Op 是对几个clip区域起作用的。几个例子都是，先定义一个裁剪区域，然后再定义一个裁剪区域以及Region.Op ，但是在drawScene又创建了一裁剪区域。我的问题是Region.Op 是对前两个前作用吗，还是说对3个都起作用。

2 楼 ipjmc 2012-09-16

lansuiyun 写道

如果有三次操作分别是a，b，c，最后的结果是(a OP b) OP c。第三次会在前两次OP的结果上进行，你可以自己写一个例子验证一下。

[2] wp7 开发学习之 ScrollViewer小使用

来源: 互联网发布时间: 2014-02-18

wp7 开发学习之 ScrollViewer小应用

xaml

[3] 图片拖动成效

来源: 互联网发布时间: 2014-02-18

图片拖动效果

拖拽图片效果

方法一：

    import android.app.Activity;
    import android.os.Bundle;
    import android.view.MotionEvent;
    import android.view.View;
    import android.view.View.OnTouchListener;
    import android.widget.ImageView;
    public class DragSample01 extends Activity {
        ImageView img;
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.drag_sample01);
            img = (ImageView)findViewById(R.id.img_view);

            img.setOnTouchListener(new OnTouchListener(){
                private int mx, my;
                public boolean onTouch(View v, MotionEvent event) {
                    switch(event.getAction()) {
                    case MotionEvent.ACTION_MOVE:
                        mx = (int)(event.getRawX());
                        my = (int)(event.getRawY() - 50);

                        v.layout(mx - img.getWidth()/2, my - img.getHeight()/2, mx + img.getWidth()/2, my + img.getHeight()/2);
                        break;
                    }
                    return true;
                }});
        }
    }

方法二：

    import android.app.Activity;
    import android.os.Bundle;
    import android.view.MotionEvent;
    import android.view.View;
    import android.view.View.OnTouchListener;
    import android.widget.ImageView;
    public class DragSample01 extends Activity {
        ImageView img;
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.drag_sample01);
            img = (ImageView)findViewById(R.id.img_view);

            img.setOnTouchListener(new OnTouchListener(){
                private float x, y;
                private int mx, my;
                public boolean onTouch(View v, MotionEvent event) {
                    switch(event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        x = event.getX();
                        y = event.getY();
                    case MotionEvent.ACTION_MOVE:
                        mx = (int)(event.getRawX() - x);
                        my = (int)(event.getRawY() - 50 - y);

                        v.layout(mx, my, mx + v.getWidth(), my + v.getHeight());
                        break;
                    }
                    return true;
                }});
        }
    }

//////////------------------

拖拽图片效果

方法一：
    import android.app.Activity;
    import android.os.Bundle;
    import android.view.MotionEvent;
    import android.view.View;
    import android.view.View.OnTouchListener;
    import android.widget.ImageView;
    public class DragSample01 extends Activity {
        ImageView img;
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.drag_sample01);
            img = (ImageView)findViewById(R.id.img_view);

            img.setOnTouchListener(new OnTouchListener(){
                private int mx, my;
                public boolean onTouch(View v, MotionEvent event) {
                    switch(event.getAction()) {
                    case MotionEvent.ACTION_MOVE:
                        mx = (int)(event.getRawX());
                        my = (int)(event.getRawY() - 50);

                        v.layout(mx - img.getWidth()/2, my - img.getHeight()/2, mx + img.getWidth()/2, my + img.getHeight()/2);
                        break;
                    }
                    return true;
                }});
        }
    }

方法二：

    import android.app.Activity;
    import android.os.Bundle;
    import android.view.MotionEvent;
    import android.view.View;
    import android.view.View.OnTouchListener;
    import android.widget.ImageView;
    public class DragSample01 extends Activity {
        ImageView img;
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.drag_sample01);
            img = (ImageView)findViewById(R.id.img_view);

            img.setOnTouchListener(new OnTouchListener(){
                private float x, y;
                private int mx, my;
                public boolean onTouch(View v, MotionEvent event) {
                    switch(event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        x = event.getX();
                        y = event.getY();
                    case MotionEvent.ACTION_MOVE:
                        mx = (int)(event.getRawX() - x);
                        my = (int)(event.getRawY() - 50 - y);

                        v.layout(mx, my, mx + v.getWidth(), my + v.getHeight());
                        break;
                    }
                    return true;
                }});
        }
    }

拖动按钮到处跑
1. 布局文件

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <Button android:id="@+id/btn" android:layout_width="fill_parent"
    android:layout_height="wrap_content" android:text="拖动看看~~" />
    </LinearLayout>

2. 代码

    import android.app.Activity;
    import android.os.Bundle;
    import android.util.DisplayMetrics;
    import android.view.MotionEvent;
    import android.view.View;
    import android.view.View.OnTouchListener;
    import android.widget.Button;

    public class DraftTest extends Activity {
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);

            final Button btn = (Button) findViewById(R.id.btn);

            btn.setOnTouchListener(new OnTouchListener() {
                int[] temp = new int[] { 0, 0 };

                public boolean onTouch(View v, MotionEvent event) {

                    int eventaction = event.getAction();

                    int x = (int) event.getRawX();
                    int y = (int) event.getRawY();

                    switch (eventaction) {

                    case MotionEvent.ACTION_DOWN: // touch down so check if the
                        temp[0] = (int) event.getX();
                        temp[1] = y - v.getTop();
                        break;

                    case MotionEvent.ACTION_MOVE: // touch drag with the ball
                        v.layout(x - temp[0], y - temp[1], x + v.getWidth()
                                - temp[0], y - temp[1] + v.getHeight());

    //                  v.postInvalidate();
                        break;

                    case MotionEvent.ACTION_UP:
                        break;
                    }

                    return false;
                }

            });

        }
    }

另一种：

    import android.app.Activity;
    import android.os.Bundle;
    import android.util.DisplayMetrics;
    import android.view.MotionEvent;
    import android.view.View;
    import android.view.View.OnTouchListener;
    import android.widget.Button;

    public class DraftTest extends Activity {
        /** Called when the activity is first created. */

        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);

            DisplayMetrics dm = getResources().getDisplayMetrics();
            final int screenWidth = dm.widthPixels;
            final int screenHeight = dm.heightPixels - 50;

            final Button b = (Button) findViewById(R.id.btn);

            b.setOnTouchListener(new OnTouchListener() {

                int lastX, lastY;

                public boolean onTouch(View v, MotionEvent event) {
                    // TODO Auto-generated method stub
                    switch (event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        lastX = (int) event.getRawX();
                        lastY = (int) event.getRawY();
                        break;
                    case MotionEvent.ACTION_MOVE:
                        int dx = (int) event.getRawX() - lastX;
                        int dy = (int) event.getRawY() - lastY;

                        int left = v.getLeft() + dx;
                        int top = v.getTop() + dy;
                        int right = v.getRight() + dx;
                        int bottom = v.getBottom() + dy;

                        if (left < 0) {
                            left = 0;
                            right = left + v.getWidth();
                        }

                        if (right > screenWidth) {
                            right = screenWidth;
                            left = right - v.getWidth();
                        }

                        if (top < 0) {
                            top = 0;
                            bottom = top + v.getHeight();
                        }

                        if (bottom > screenHeight) {
                            bottom = screenHeight;
                            top = bottom - v.getHeight();
                        }

                        v.layout(left, top, right, bottom);

                        lastX = (int) event.getRawX();
                        lastY = (int) event.getRawY();

                        break;
                    case MotionEvent.ACTION_UP:
                        break;
                    }
                    return false;
                }
            });
        }
    }