使用 Matrix 和 ImageView 的 x,y 进行缩放 in/out

Question

我有一个 ImageView：

<ImageView
    android:id="@+id/ivHand"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:scaleType="fitXY" />

在 Activity 中，我执行以下操作：

    ImageView ivBgHand = (ImageView) findViewById(R.id.ivHand);
    Bitmap bitmap = BitmapFactory.decodeFile(photoPath); // Path from storage
    ivBgHand.setImageBitmap(bitmap);

我想使用 Matrix 和应该缩放的 x、y 坐标（又名 pivotX、pivotY）进行放大和缩小。谁能帮我这个？（我不想使用ScaleAnimation，因为下一步将是一个处理变化的Matrix）

Answer 1

如果您正在寻找一个无需额外代码即可处理图像视图缩放的简单库，那么我可以推荐使用 PhotoView 库。很简单。

Answer 2

我找到了一个绝妙的解决方案！ Source link。自定义布局视图：

package <your package>;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.FrameLayout;

/**
 * Zooming view.
 */
public class ZoomView extends FrameLayout {

public ZoomView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    // TODO Auto-generated constructor stub
}

public ZoomView(Context context, AttributeSet attrs) {
    super(context, attrs);
    // TODO Auto-generated constructor stub
}

public ZoomView(final Context context) {
    super(context);
}

/**
 * Zooming view listener interface.
 * 
 * @author karooolek
 * 
 */
public interface ZoomViewListener {

    void onZoomStarted(float zoom, float zoomx, float zoomy);

    void onZooming(float zoom, float zoomx, float zoomy);

    void onZoomEnded(float zoom, float zoomx, float zoomy);
}

// zooming
float zoom = 1.0f;
float maxZoom = 2.0f;
float smoothZoom = 1.0f;
float zoomX, zoomY;
float smoothZoomX, smoothZoomY;
private boolean scrolling; // NOPMD by karooolek on 29.06.11 11:45

// minimap variables
private boolean showMinimap = false;
private int miniMapColor = Color.WHITE;
private int miniMapHeight = -1;
private String miniMapCaption;
private float miniMapCaptionSize = 10.0f;
private int miniMapCaptionColor = Color.WHITE;

// touching variables
private long lastTapTime;
private float touchStartX, touchStartY;
private float touchLastX, touchLastY;
private float startd;
private boolean pinching;
private float lastd;
private float lastdx1, lastdy1;
private float lastdx2, lastdy2;

// drawing
private final Matrix m = new Matrix();
private final Paint p = new Paint();

// listener
ZoomViewListener listener;

private Bitmap ch;

public float getZoom() {
    return zoom;
}

public float getMaxZoom() {
    return maxZoom;
}

public void setMaxZoom(final float maxZoom) {
    if (maxZoom < 1.0f) {
        return;
    }

    this.maxZoom = maxZoom;
}

public void setMiniMapEnabled(final boolean showMiniMap) {
    this.showMinimap = showMiniMap;
}

public boolean isMiniMapEnabled() {
    return showMinimap;
}

public void setMiniMapHeight(final int miniMapHeight) {
    if (miniMapHeight < 0) {
        return;
    }
    this.miniMapHeight = miniMapHeight;
}

public int getMiniMapHeight() {
    return miniMapHeight;
}

public void setMiniMapColor(final int color) {
    miniMapColor = color;
}

public int getMiniMapColor() {
    return miniMapColor;
}

public String getMiniMapCaption() {
    return miniMapCaption;
}

public void setMiniMapCaption(final String miniMapCaption) {
    this.miniMapCaption = miniMapCaption;
}

public float getMiniMapCaptionSize() {
    return miniMapCaptionSize;
}

public void setMiniMapCaptionSize(final float size) {
    miniMapCaptionSize = size;
}

public int getMiniMapCaptionColor() {
    return miniMapCaptionColor;
}

public void setMiniMapCaptionColor(final int color) {
    miniMapCaptionColor = color;
}

public void zoomTo(final float zoom, final float x, final float y) {
    this.zoom = Math.min(zoom, maxZoom);
    zoomX = x;
    zoomY = y;
    smoothZoomTo(this.zoom, x, y);
}

public void smoothZoomTo(final float zoom, final float x, final float y) {
    smoothZoom = clamp(1.0f, zoom, maxZoom);
    smoothZoomX = x;
    smoothZoomY = y;
    if (listener != null) {
        listener.onZoomStarted(smoothZoom, x, y);
    }
}

public ZoomViewListener getListener() {
    return listener;
}

public void setListner(final ZoomViewListener listener) {
    this.listener = listener;
}

public float getZoomFocusX() {
    return zoomX * zoom;
}

public float getZoomFocusY() {
    return zoomY * zoom;
}

@Override
public boolean dispatchTouchEvent(final MotionEvent ev) {
    // single touch
    if (ev.getPointerCount() == 1) {
        processSingleTouchEvent(ev);
    }

    // // double touch
    if (ev.getPointerCount() == 2) {
        processDoubleTouchEvent(ev);
    }

    // redraw
    getRootView().invalidate();
    invalidate();

    return true;
}

private void processSingleTouchEvent(final MotionEvent ev) {

    final float x = ev.getX();
    final float y = ev.getY();

    final float w = miniMapHeight * (float) getWidth() / getHeight();
    final float h = miniMapHeight;
    final boolean touchingMiniMap = x >= 10.0f && x <= 10.0f + w
            && y >= 10.0f && y <= 10.0f + h;

    if (showMinimap && smoothZoom > 1.0f && touchingMiniMap) {
        processSingleTouchOnMinimap(ev);
    } else {
        processSingleTouchOutsideMinimap(ev);
    }
}

private void processSingleTouchOnMinimap(final MotionEvent ev) {
    final float x = ev.getX();
    final float y = ev.getY();

    final float w = miniMapHeight * (float) getWidth() / getHeight();
    final float h = miniMapHeight;
    final float zx = (x - 10.0f) / w * getWidth();
    final float zy = (y - 10.0f) / h * getHeight();
    smoothZoomTo(smoothZoom, zx, zy);
}

private void processSingleTouchOutsideMinimap(final MotionEvent ev) {
    final float x = ev.getX();
    final float y = ev.getY();
    float lx = x - touchStartX;
    float ly = y - touchStartY;
    final float l = (float) Math.hypot(lx, ly);
    float dx = x - touchLastX;
    float dy = y - touchLastY;
    touchLastX = x;
    touchLastY = y;

    switch (ev.getAction()) {
    case MotionEvent.ACTION_DOWN:
        touchStartX = x;
        touchStartY = y;
        touchLastX = x;
        touchLastY = y;
        dx = 0;
        dy = 0;
        lx = 0;
        ly = 0;
        scrolling = false;
        break;

        case MotionEvent.ACTION_MOVE:
            if (scrolling || (smoothZoom > 1.0f && l > 30.0f)) {
                if (!scrolling) {
                    scrolling = true;
                    ev.setAction(MotionEvent.ACTION_CANCEL);
                    super.dispatchTouchEvent(ev);
                }
                smoothZoomX -= dx / zoom;
                smoothZoomY -= dy / zoom;
                return;
            }
            break;

        case MotionEvent.ACTION_OUTSIDE:
        case MotionEvent.ACTION_UP:

            // tap
            if (l < 30.0f) {
                // check double tap
                if (System.currentTimeMillis() - lastTapTime < 500) {
                    if (smoothZoom == 1.0f) {
                        smoothZoomTo(maxZoom, x, y);
                    } else {
                        smoothZoomTo(1.0f, getWidth() / 2.0f,
                            getHeight() / 2.0f);
                    }
                    lastTapTime = 0;
                    ev.setAction(MotionEvent.ACTION_CANCEL);
                    super.dispatchTouchEvent(ev);
                    return;
                }

                lastTapTime = System.currentTimeMillis();

                performClick();
            }
            break;

        default:
            break;
        }

        ev.setLocation(zoomX + (x - 0.5f * getWidth()) / zoom, zoomY
            + (y - 0.5f * getHeight()) / zoom);

        ev.getX();
        ev.getY();

        super.dispatchTouchEvent(ev);
    }

    private void processDoubleTouchEvent(final MotionEvent ev) {
        final float x1 = ev.getX(0);
        final float dx1 = x1 - lastdx1;
        lastdx1 = x1;
        final float y1 = ev.getY(0);
        final float dy1 = y1 - lastdy1;
        lastdy1 = y1;
        final float x2 = ev.getX(1);
        final float dx2 = x2 - lastdx2;
        lastdx2 = x2;
        final float y2 = ev.getY(1);
        final float dy2 = y2 - lastdy2;
        lastdy2 = y2;

        // pointers distance
        final float d = (float) Math.hypot(x2 - x1, y2 - y1);
        final float dd = d - lastd;
        lastd = d;
        final float ld = Math.abs(d - startd);

        Math.atan2(y2 - y1, x2 - x1);
        switch (ev.getAction()) {
        case MotionEvent.ACTION_DOWN:
            startd = d;
            pinching = false;
            break;

        case MotionEvent.ACTION_MOVE:
            if (pinching || ld > 30.0f) {
                pinching = true;
                final float dxk = 0.5f * (dx1 + dx2);
                final float dyk = 0.5f * (dy1 + dy2);
                smoothZoomTo(Math.max(1.0f, zoom * d / (d - dd)), zoomX - dxk
                    / zoom, zoomY - dyk / zoom);
            }

            break;

        case MotionEvent.ACTION_UP:
        default:
        pinching = false;
        break;
        }

        ev.setAction(MotionEvent.ACTION_CANCEL);
        super.dispatchTouchEvent(ev);
    }

    private float clamp(final float min, final float value, final float max) {
        return Math.max(min, Math.min(value, max));
    }

    private float lerp(final float a, final float b, final float k) {
    return a + (b - a) * k;
    }

    private float bias(final float a, final float b, final float k) {
    return Math.abs(b - a) >= k ? a + k * Math.signum(b - a) : b;
    }

    @Override
    protected void dispatchDraw(final Canvas canvas) {

        // do zoom
        zoom = lerp(bias(zoom, smoothZoom, 0.05f), smoothZoom, 0.2f);
        smoothZoomX = clamp(0.5f * getWidth() / smoothZoom, smoothZoomX,
            getWidth() - 0.5f * getWidth() / smoothZoom);
        smoothZoomY = clamp(0.5f * getHeight() / smoothZoom, smoothZoomY,
            getHeight() - 0.5f * getHeight() / smoothZoom);

        zoomX = lerp(bias(zoomX, smoothZoomX, 0.1f), smoothZoomX, 0.35f);
        zoomY = lerp(bias(zoomY, smoothZoomY, 0.1f), smoothZoomY, 0.35f);
        if (zoom != smoothZoom && listener != null) {
            listener.onZooming(zoom, zoomX, zoomY);
        }

        final boolean animating = Math.abs(zoom - smoothZoom) > 0.0000001f
                || Math.abs(zoomX - smoothZoomX) > 0.0000001f
                || Math.abs(zoomY - smoothZoomY) > 0.0000001f;

        // nothing to draw
        if (getChildCount() == 0) {
            return;
        }

        // prepare matrix
        m.setTranslate(0.5f * getWidth(), 0.5f * getHeight());
        m.preScale(zoom, zoom);
        m.preTranslate(
                -clamp(0.5f * getWidth() / zoom, zoomX, getWidth() - 0.5f
                    * getWidth() / zoom),
                -clamp(0.5f * getHeight() / zoom, zoomY, getHeight() - 0.5f
                    * getHeight() / zoom));

        // get view
        final View v = getChildAt(0);
        m.preTranslate(v.getLeft(), v.getTop());

        // get drawing cache if available
        if (animating && ch == null && isAnimationCacheEnabled()) {
            v.setDrawingCacheEnabled(true);
            ch = v.getDrawingCache();
        }

        // draw using cache while animating
        if (animating && isAnimationCacheEnabled() && ch != null) {
            p.setColor(0xffffffff);
            canvas.drawBitmap(ch, m, p);
        } else { // zoomed or cache unavailable
            ch = null;
            canvas.save();
            canvas.concat(m);
            v.draw(canvas);
            canvas.restore();
        }

        // draw minimap
        if (showMinimap) {
            if (miniMapHeight < 0) {
                miniMapHeight = getHeight() / 4;
            }

            canvas.translate(10.0f, 10.0f);

            p.setColor(0x80000000 | 0x00ffffff & miniMapColor);
            final float w = miniMapHeight * (float) getWidth() / getHeight();
            final float h = miniMapHeight;
            canvas.drawRect(0.0f, 0.0f, w, h, p);

            if (miniMapCaption != null && miniMapCaption.length() > 0) {
                p.setTextSize(miniMapCaptionSize);
                p.setColor(miniMapCaptionColor);
                p.setAntiAlias(true);
                canvas.drawText(miniMapCaption, 10.0f,
                        10.0f + miniMapCaptionSize, p);
                p.setAntiAlias(false);
            }

            p.setColor(0x80000000 | 0x00ffffff & miniMapColor);
            final float dx = w * zoomX / getWidth();
            final float dy = h * zoomY / getHeight();
            canvas.drawRect(dx - 0.5f * w / zoom, dy - 0.5f * h / zoom, dx
                    + 0.5f * w / zoom, dy + 0.5f * h / zoom, p);

            canvas.translate(-10.0f, -10.0f);
        }

        // redraw
        // if (animating) {
        getRootView().invalidate();
        invalidate();
        // }
    }
}

请记住，自定义视图应该只有一个子视图，这就是为什么这些视图被包装在 RelativeLayout 中的原因

<!-- View which can change matrix of multiple views -->
<com.vitalii.semeruk.model.ZoomView
    android:id="@+id/zoomView"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!-- Note: ZoomView should have only one child
     that's why were wrapped these views in RelativeLayout -->
    <RelativeLayout
        android:id="@+id/relativeLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <!-- Captured photo -->
        <com.vitalii.semeruk.model.HandView
            android:id="@+id/ivBgHand"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@android:color/white"
            android:scaleType="fitXY" />

        <!-- Ring -->
        <com.vitalii.semeruk.model.RingPinky
            android:id="@+id/ivRingPinky"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

    </RelativeLayout>

</com.vitalii.semeruk.model.ZoomView>

Activity中使用的方法是：

zoomTo() 和 smoothZoomTo()

示例：

    ZoomView zoomView = (ZoomView) findViewById(R.id.zoomView);
    zoomView.smoothZoomTo(3f, 86, 908);

要更改最大缩放比例，请查找并替换：float maxZoom = 2.0f; 为适合您需要的值。

使用 Matrix 和 ImageView 的 x,y 进行缩放 in/out

Make zoom in/out using Matrix and x,y of ImageView

android

matrix

zooming