Bug 701594 - Part 3: Add viewport interpolation functions. r=kats

mobile/android/base/gfx/FloatSize.java

@@ -69,5 +69,14 @@ public class FloatSize {
     public FloatSize scale(float factor) {
         return new FloatSize(width * factor, height * factor);
     }
+
+    /*
+     * Returns the size that represents a linear transition between this size and `to` at time `t`,
+     * which is on the scale [0, 1).
+     */
+    public FloatSize interpolate(FloatSize to, float t) {
+        return new FloatSize(FloatUtils.interpolate(width, to.width, t),
+                             FloatUtils.interpolate(height, to.height, t));
+    }
 }
 

mobile/android/base/gfx/RectUtils.java

@@ -37,6 +37,7 @@
 
 package org.mozilla.gecko.gfx;
 
+import org.mozilla.gecko.FloatUtils;
 import android.graphics.Rect;
 import android.graphics.RectF;
 import org.json.JSONException;
@@ -118,4 +119,15 @@ public final class RectUtils {
         float y = Math.max(dest.top, Math.min(dest.bottom-height, rect.top));
         return new RectF(x, y, x+width, y+height);
     }
+
+    /*
+     * Returns the rect that represents a linear transition between `from` and `to` at time `t`,
+     * which is on the scale [0, 1).
+     */
+    public static RectF interpolate(RectF from, RectF to, float t) {
+        return new RectF(FloatUtils.interpolate(from.left, to.left, t),
+                         FloatUtils.interpolate(from.top, to.top, t),
+                         FloatUtils.interpolate(from.right, to.right, t),
+                         FloatUtils.interpolate(from.bottom, to.bottom, t));
+    }
 }

mobile/android/base/gfx/ViewportMetrics.java

@@ -42,6 +42,7 @@ import android.graphics.Point;
 import android.graphics.PointF;
 import android.graphics.Rect;
 import android.graphics.RectF;
+import org.mozilla.gecko.FloatUtils;
 import org.mozilla.gecko.gfx.FloatSize;
 import org.mozilla.gecko.gfx.LayerController;
 import org.mozilla.gecko.gfx.RectUtils;
@@ -216,6 +217,20 @@ public class ViewportMetrics {
         mZoomFactor = newZoomFactor;
     }
 
+    /*
+     * Returns the viewport metrics that represent a linear transition between `from` and `to` at
+     * time `t`, which is on the scale [0, 1). This function interpolates the viewport rect, the
+     * page size, the offset, and the zoom factor.
+     */
+    public ViewportMetrics interpolate(ViewportMetrics to, float t) {
+        ViewportMetrics result = new ViewportMetrics();
+        result.mPageSize = mPageSize.interpolate(to.mPageSize, t);
+        result.mZoomFactor = FloatUtils.interpolate(mZoomFactor, to.mZoomFactor, t);
+        result.mViewportRect = RectUtils.interpolate(mViewportRect, to.mViewportRect, t);
+        result.mViewportOffset = PointUtils.interpolate(mViewportOffset, to.mViewportOffset, t);
+        return result;
+    }
+
     public String toJSON() {
         return "{ \"x\" : " + mViewportRect.left +
                ", \"y\" : " + mViewportRect.top +

mobile/android/base/ui/PanZoomController.java

@@ -43,6 +43,7 @@ import org.mozilla.gecko.gfx.FloatSize;
 import org.mozilla.gecko.gfx.LayerController;
 import org.mozilla.gecko.gfx.PointUtils;
 import org.mozilla.gecko.gfx.RectUtils;
+import org.mozilla.gecko.gfx.ViewportMetrics;
 import org.mozilla.gecko.FloatUtils;
 import org.mozilla.gecko.GeckoApp;
 import org.mozilla.gecko.GeckoAppShell;
@@ -752,6 +753,36 @@ public class PanZoomController
         }
     }
 
+    /* Returns the nearest viewport metrics with no overscroll visible. */
+    private ViewportMetrics getValidViewportMetrics() {
+        ViewportMetrics viewportMetrics = new ViewportMetrics(mController.getViewportMetrics());
+
+        /* First, we adjust the zoom factor so that we can make no overscrolled area visible. */
+        float zoomFactor = viewportMetrics.getZoomFactor();
+        FloatSize pageSize = viewportMetrics.getPageSize();
+        RectF viewport = viewportMetrics.getViewport();
+
+        float minZoomFactor = 0.0f;
+        if (viewport.width() > pageSize.width) {
+            float scaleFactor = viewport.width() / pageSize.width;
+            minZoomFactor = (float)Math.max(minZoomFactor, zoomFactor * scaleFactor);
+        }
+        if (viewport.height() > pageSize.height) {
+            float scaleFactor = viewport.height() / pageSize.height;
+            minZoomFactor = (float)Math.max(minZoomFactor, zoomFactor * scaleFactor);
+        }
+
+        if (!FloatUtils.fuzzyEquals(minZoomFactor, 0.0f)) {
+            PointF center = new PointF(viewport.width() / 2.0f, viewport.height() / 2.0f);
+            viewportMetrics.scaleTo(minZoomFactor, center);
+        }
+
+        /* Now we pan to the right origin. */
+        viewportMetrics.setViewport(viewportMetrics.getClampedViewport());
+
+        return viewportMetrics;
+    }
+
     private class AxisX extends Axis {
         @Override
         public float getOrigin() { return mController.getOrigin().x; }