GridView 捏缩放和无限（环绕）滚动

Question

我是 Android 的新手。我有一个项目需要使用 GridView。在单个页面中显示了 'n' 个图像。任务是捏放大，用手指拉伸缩小，不需要缩放整个屏幕的单个图像，也不需要无限（环绕）滚动，就像我在到达后开始向上滚动页面（包含从 1 到 n 的 n 张图像）一样在页面的末尾，它将在下一页中再次显示从 1 到 n 个图像（与上一页相同）。当向下滚动页面上方时，将显示从 n 到 1 (n,n-1,n-2,...1) 的图像。请帮助我解决上述情况。到目前为止，我已经按照下面 link 在一个页面中显示 n 个图像。 this is the link I followed

Answer 1

将您的视图添加到此 ZoomView class 类似于

ZoomView zoomView = new ZoomView(this);//这表示Activity

zoomView.addView(view);//视图-->你的视图

setContentView(zoomView);//就地使用这个 setContentView(R.layout.xxxxx);

希望对您有所帮助

public class ZoomView 扩展了 FrameLayout {

/**
 * 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 = 50.0f;
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.BLACK;
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 ZoomView(final Context context) {
    super(context);
}

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();
    // }
}

}

GridView 捏缩放和无限（环绕）滚动

GridView pinch zoom and infinite (wrap around) scrolling

android

gridview

infinite-scroll

pinchzoom