Make fling bound to page when single page fills screen with pageFling…

… enabled.

Close DImuthuUpe#2 and DImuthuUpe#3

android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/DragPinchManager.java

@@ -21,7 +21,6 @@
 import android.view.MotionEvent;
 import android.view.ScaleGestureDetector;
 import android.view.View;
-import android.view.ViewConfiguration;
 
 import com.github.barteksc.pdfviewer.model.LinkTapEvent;
 import com.github.barteksc.pdfviewer.scroll.ScrollHandle;
@@ -181,7 +180,7 @@ public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float d
     private void onScrollEnd(MotionEvent event) {
         pdfView.loadPages();
         hideHandle();
-        if (!pdfView.isZooming() && !animationManager.isFlinging()) {
+        if (!animationManager.isFlinging() && !pdfView.pageFillsScreen()) {
             pdfView.doPageSnap();
         }
     }
@@ -196,10 +195,15 @@ public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float ve
         if (!pdfView.isSwipeEnabled()) {
             return false;
         }
-        if (!pdfView.isZooming() && pdfView.doPageFling()) {
-            startPageFling(e1, e2, velocityX, velocityY);
+        if (pdfView.doPageFling()) {
+            if (pdfView.pageFillsScreen()) {
+                onBoundedFling(velocityX, velocityY);
+            } else {
+                startPageFling(e1, e2, velocityX, velocityY);
+            }
             return true;
         }
+
         int xOffset = (int) pdfView.getCurrentXOffset();
         int yOffset = (int) pdfView.getCurrentYOffset();
 
@@ -218,6 +222,31 @@ public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float ve
         return true;
     }
 
+    private void onBoundedFling(float velocityX, float velocityY) {
+        int xOffset = (int) pdfView.getCurrentXOffset();
+        int yOffset = (int) pdfView.getCurrentYOffset();
+
+        PdfFile pdfFile = pdfView.pdfFile;
+
+        float pageStart = -pdfFile.getPageOffset(pdfView.getCurrentPage(), pdfView.getZoom());
+        float pageEnd = pageStart - pdfFile.getPageLength(pdfView.getCurrentPage(), pdfView.getZoom());
+        float minX, minY, maxX, maxY;
+        if (pdfView.isSwipeVertical()) {
+            minX = -(pdfView.toCurrentScale(pdfFile.getMaxPageWidth()) - pdfView.getWidth());
+            minY = pageEnd + pdfView.getHeight();
+            maxX = 0;
+            maxY = pageStart;
+        } else {
+            minX = pageEnd + pdfView.getWidth();
+            minY = -(pdfView.toCurrentScale(pdfFile.getMaxPageHeight()) - pdfView.getHeight());
+            maxX = pageStart;
+            maxY = 0;
+        }
+
+        animationManager.startFlingAnimation(xOffset, yOffset, (int) (velocityX), (int) (velocityY),
+                (int) minX, (int) maxX, (int) minY, (int) maxY);
+    }
+
     @Override
     public boolean onScale(ScaleGestureDetector detector) {
         float dr = detector.getScaleFactor();
@@ -270,11 +299,8 @@ private void hideHandle() {
     }
 
     private boolean checkDoPageFling(float velocityX, float velocityY) {
-        int minVelocity = ViewConfiguration.get(pdfView.getContext()).getScaledMinimumFlingVelocity();
-        if (pdfView.isSwipeVertical()) {
-            return Math.abs(velocityY) > minVelocity;
-        } else {
-            return Math.abs(velocityX) > minVelocity;
-        }
+        float absX = Math.abs(velocityX);
+        float absY = Math.abs(velocityY);
+        return pdfView.isSwipeVertical() ? absY > absX : absX > absY;
     }
 }

android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/PDFView.java

@@ -895,7 +895,7 @@ float snapOffsetForPage(int pageIndex) {
         float offset = pdfFile.getPageOffset(pageIndex, zoom);
 
         float size = swipeVertical ? getHeight() : getWidth();
-        float pageSize = getPageLength(pageIndex, zoom);
+        float pageSize = pdfFile.getPageLength(pageIndex, zoom);
 
         if (snapPolicy == SnapPolicy.CENTER) {
             offset = offset - size / 2f + pageSize / 2f;
@@ -930,9 +930,9 @@ int findPageToSnap(float xOffset, float yOffset) {
                 int endIndex = pdfFile.getPageAtOffset(-end, zoom);
                 if (endIndex > 0) {
                     // check if previous page is actually closer
-                    float pageEnd = -pdfFile.getPageOffset(endIndex, zoom) - getPageLength(endIndex, zoom);
+                    float pageEnd = -pdfFile.getPageOffset(endIndex, zoom) - pdfFile.getPageLength(endIndex, zoom);
                     float prevPageEnd = -pdfFile.getPageOffset(endIndex - 1, zoom) -
-                            getPageLength(endIndex - 1, zoom);
+                            pdfFile.getPageLength(endIndex - 1, zoom);
                     if (end - pageEnd > prevPageEnd - end) {
                         return endIndex - 1;
                     }
@@ -944,11 +944,16 @@ int findPageToSnap(float xOffset, float yOffset) {
     }
 
     /**
-     * Get the page's height if swiping vertical, or width if swiping horizontal.
+     * @return true if single page fills the entire screen in the scrolling direction
      */
-    private float getPageLength(int pageIndex, float zoom) {
-        SizeF size = pdfFile.getPageSize(pageIndex);
-        return (swipeVertical ? size.getHeight() : size.getWidth()) * zoom;
+    public boolean pageFillsScreen() {
+        float start = -pdfFile.getPageOffset(currentPage, zoom);
+        float end = start - pdfFile.getPageLength(currentPage, zoom);
+        if (isSwipeVertical()) {
+            return start > currentYOffset && end < currentYOffset - getHeight();
+        } else {
+            return start > currentXOffset && end < currentXOffset - getWidth();
+        }
     }
 
     /**

android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/PdfFile.java

@@ -212,6 +212,14 @@ public float getDocLen(float zoom) {
         return documentLength * zoom;
     }
 
+    /**
+     * Get the page's height if swiping vertical, or width if swiping horizontal.
+     */
+    public float getPageLength(int pageIndex, float zoom) {
+        SizeF size = getPageSize(pageIndex);
+        return (isVertical ? size.getHeight() : size.getWidth()) * zoom;
+    }
+
     public float getPageSpacing(int pageIndex, float zoom) {
         float spacing = autoSpacing ? pageSpacing.get(pageIndex) : spacingPx;
         return spacing * zoom;
@@ -356,5 +364,4 @@ public int documentPage(int userPage) {
 
         return documentPage;
     }
-
 }