Ensure freeform windows always have a visible portion on screen

There was already code attempting to do this, but it wasn't
correct and was causing windows to pop to top or left.

This basically ensures that a fixed amount of dp in each
linear direction is visible on the screen for a given window.

Since this is handled in policy, it doesn't need to be enforced
during computeFrame anymore.

Bug: 123757388
Test: drag freeform to right or bottom,
      atest TaskRecordTests WindowFrameTests
Change-Id: I23c690a5efe06c77caa14ecc8e30a30cd42c23c4

3 files changed, 65 insertions, 51 deletions

diff --git a/services/core/java/com/android/server/wm/TaskRecord.java b/services/core/java/com/android/server/wm/TaskRecord.java
index 1392762fca66..4fd84896e101 100644
--- a/services/core/java/com/android/server/wm/TaskRecord.java
+++ b/services/core/java/com/android/server/wm/TaskRecord.java
@@ -202,13 +202,6 @@ class TaskRecord extends ConfigurationContainer {
     // Do not move the stack as a part of reparenting
     static final int REPARENT_LEAVE_STACK_IN_PLACE = 2;
 
-    // The height/width divide used when fitting a task within a bounds with method
-    // {@link #fitWithinBounds}.
-    // We always want the task to to be visible in the bounds without affecting its size when
-    // fitting. To make sure this is the case, we don't adjust the task left or top side pass
-    // the input bounds right or bottom side minus the width or height divided by this value.
-    private static final int FIT_WITHIN_BOUNDS_DIVIDER = 3;
-
     /**
      * The factory used to create {@link TaskRecord}. This allows OEM subclass {@link TaskRecord}.
      */
@@ -1932,35 +1925,33 @@ class TaskRecord extends ConfigurationContainer {
      *
      * @param bounds Bounds to be adjusted.
      * @param stackBounds Bounds within which the other bounds should remain.
+     * @param overlapPxX The amount of px required to be visible in the X dimension.
+     * @param overlapPxY The amount of px required to be visible in the Y dimension.
      */
-    private static void fitWithinBounds(Rect bounds, Rect stackBounds) {
+    private static void fitWithinBounds(Rect bounds, Rect stackBounds, int overlapPxX,
+            int overlapPxY) {
         if (stackBounds == null || stackBounds.isEmpty() || stackBounds.contains(bounds)) {
             return;
         }
 
-        if (bounds.left < stackBounds.left || bounds.right > stackBounds.right) {
-            final int maxRight = stackBounds.right
-                    - (stackBounds.width() / FIT_WITHIN_BOUNDS_DIVIDER);
-            int horizontalDiff = stackBounds.left - bounds.left;
-            if ((horizontalDiff < 0 && bounds.left >= maxRight)
-                    || (bounds.left + horizontalDiff >= maxRight)) {
-                horizontalDiff = maxRight - bounds.left;
-            }
-            bounds.left += horizontalDiff;
-            bounds.right += horizontalDiff;
+        // For each side of the parent (eg. left), check if the opposing side of the window (eg.
+        // right) is at least overlap pixels away. If less, offset the window by that difference.
+        int horizontalDiff = 0;
+        // If window is smaller than overlap, use it's smallest dimension instead
+        int overlapLR = Math.min(overlapPxX, bounds.width());
+        if (bounds.right < (stackBounds.left + overlapLR)) {
+            horizontalDiff = overlapLR - (bounds.right - stackBounds.left);
+        } else if (bounds.left > (stackBounds.right - overlapLR)) {
+            horizontalDiff = -(overlapLR - (stackBounds.right - bounds.left));
         }
-
-        if (bounds.top < stackBounds.top || bounds.bottom > stackBounds.bottom) {
-            final int maxBottom = stackBounds.bottom
-                    - (stackBounds.height() / FIT_WITHIN_BOUNDS_DIVIDER);
-            int verticalDiff = stackBounds.top - bounds.top;
-            if ((verticalDiff < 0 && bounds.top >= maxBottom)
-                    || (bounds.top + verticalDiff >= maxBottom)) {
-                verticalDiff = maxBottom - bounds.top;
-            }
-            bounds.top += verticalDiff;
-            bounds.bottom += verticalDiff;
+        int verticalDiff = 0;
+        int overlapTB = Math.min(overlapPxY, bounds.width());
+        if (bounds.bottom < (stackBounds.top + overlapTB)) {
+            verticalDiff = overlapTB - (bounds.bottom - stackBounds.top);
+        } else if (bounds.top > (stackBounds.bottom - overlapTB)) {
+            verticalDiff = -(overlapTB - (stackBounds.bottom - bounds.top));
         }
+        bounds.offset(horizontalDiff, verticalDiff);
     }
 
     /**
@@ -2230,7 +2221,11 @@ class TaskRecord extends ConfigurationContainer {
         adjustForMinimalTaskDimensions(outOverrideBounds, mTmpBounds);
         if (windowingMode == WINDOWING_MODE_FREEFORM) {
             // by policy, make sure the window remains within parent somewhere
-            fitWithinBounds(outOverrideBounds, newParentConfig.windowConfiguration.getBounds());
+            final float density =
+                    ((float) newParentConfig.densityDpi) / DisplayMetrics.DENSITY_DEFAULT;
+            fitWithinBounds(outOverrideBounds, newParentConfig.windowConfiguration.getBounds(),
+                    (int) (density * WindowState.MINIMUM_VISIBLE_WIDTH_IN_DP),
+                    (int) (density * WindowState.MINIMUM_VISIBLE_HEIGHT_IN_DP));
         }
         computeConfigResourceOverrides(getResolvedOverrideConfiguration(), newParentConfig);
     }
diff --git a/services/core/java/com/android/server/wm/WindowState.java b/services/core/java/com/android/server/wm/WindowState.java
index d5a6f00ff30d..20cca66d8a52 100644
--- a/services/core/java/com/android/server/wm/WindowState.java
+++ b/services/core/java/com/android/server/wm/WindowState.java
@@ -942,29 +942,9 @@ class WindowState extends WindowContainer<WindowState> implements WindowManagerP
         // Make sure the content and visible frames are inside of the
         // final window frame.
         if (windowsAreFloating && !mWindowFrames.mFrame.isEmpty()) {
-            // For pinned workspace the frame isn't limited in any particular
-            // way since SystemUI controls the bounds. For freeform however
-            // we want to keep things inside the content frame.
-            final Rect limitFrame = task.inPinnedWindowingMode() ? mWindowFrames.mFrame
-                    : mWindowFrames.mContentFrame;
-            // Keep the frame out of the blocked system area, limit it in size to the content area
-            // and make sure that there is always a minimum visible so that the user can drag it
-            // into a usable area..
-            final int height = Math.min(mWindowFrames.mFrame.height(), limitFrame.height());
-            final int width = Math.min(limitFrame.width(), mWindowFrames.mFrame.width());
-            final DisplayMetrics displayMetrics = getDisplayContent().getDisplayMetrics();
-            final int minVisibleHeight = Math.min(height, WindowManagerService.dipToPixel(
-                    MINIMUM_VISIBLE_HEIGHT_IN_DP, displayMetrics));
-            final int minVisibleWidth = Math.min(width, WindowManagerService.dipToPixel(
-                    MINIMUM_VISIBLE_WIDTH_IN_DP, displayMetrics));
-            final int top = Math.max(limitFrame.top,
-                    Math.min( mWindowFrames.mFrame.top, limitFrame.bottom - minVisibleHeight));
-            final int left = Math.max(limitFrame.left + minVisibleWidth - width,
-                    Math.min( mWindowFrames.mFrame.left, limitFrame.right - minVisibleWidth));
-            mWindowFrames.mFrame.set(left, top, left + width, top + height);
             final int visBottom = mWindowFrames.mVisibleFrame.bottom;
             final int contentBottom = mWindowFrames.mContentFrame.bottom;
-            mWindowFrames.mContentFrame.set( mWindowFrames.mFrame);
+            mWindowFrames.mContentFrame.set(mWindowFrames.mFrame);
             mWindowFrames.mVisibleFrame.set(mWindowFrames.mContentFrame);
             mWindowFrames.mStableFrame.set(mWindowFrames.mContentFrame);
             if (isImeTarget && inFreeformWindowingMode()) {
diff --git a/services/tests/wmtests/src/com/android/server/wm/TaskRecordTests.java b/services/tests/wmtests/src/com/android/server/wm/TaskRecordTests.java
index 5d0788881704..dc307b547a63 100644
--- a/services/tests/wmtests/src/com/android/server/wm/TaskRecordTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/TaskRecordTests.java
@@ -47,6 +47,7 @@ import android.content.res.Configuration;
 import android.graphics.Rect;
 import android.platform.test.annotations.Presubmit;
 import android.service.voice.IVoiceInteractionSession;
+import android.util.DisplayMetrics;
 import android.util.Xml;
 import android.view.DisplayInfo;
 
@@ -166,6 +167,44 @@ public class TaskRecordTests extends ActivityTestsBase {
                 WINDOWING_MODE_FREEFORM, mParentBounds, insetBounds, insetBounds);
     }
 
+    @Test
+    public void testFitWithinBounds() {
+        final Rect parentBounds = new Rect(10, 10, 200, 200);
+        ActivityDisplay display = mService.mRootActivityContainer.getDefaultDisplay();
+        ActivityStack stack = display.createStack(WINDOWING_MODE_FREEFORM, ACTIVITY_TYPE_STANDARD,
+                true /* onTop */);
+        TaskRecord task = new TaskBuilder(mSupervisor).setStack(stack).build();
+        final Configuration parentConfig = stack.getConfiguration();
+        parentConfig.windowConfiguration.setBounds(parentBounds);
+        parentConfig.densityDpi = DisplayMetrics.DENSITY_DEFAULT;
+
+        // check top and left
+        Rect reqBounds = new Rect(-190, -190, 0, 0);
+        task.setBounds(reqBounds);
+        // Make sure part of it is exposed
+        assertTrue(task.getBounds().right > parentBounds.left);
+        assertTrue(task.getBounds().bottom > parentBounds.top);
+        // Should still be more-or-less in that corner
+        assertTrue(task.getBounds().left <= parentBounds.left);
+        assertTrue(task.getBounds().top <= parentBounds.top);
+
+        assertEquals(reqBounds.width(), task.getBounds().width());
+        assertEquals(reqBounds.height(), task.getBounds().height());
+
+        // check bottom and right
+        reqBounds = new Rect(210, 210, 400, 400);
+        task.setBounds(reqBounds);
+        // Make sure part of it is exposed
+        assertTrue(task.getBounds().left < parentBounds.right);
+        assertTrue(task.getBounds().top < parentBounds.bottom);
+        // Should still be more-or-less in that corner
+        assertTrue(task.getBounds().right >= parentBounds.right);
+        assertTrue(task.getBounds().bottom >= parentBounds.bottom);
+
+        assertEquals(reqBounds.width(), task.getBounds().width());
+        assertEquals(reqBounds.height(), task.getBounds().height());
+    }
+
     /** Tests that the task bounds adjust properly to changes between FULLSCREEN and FREEFORM */
     @Test
     public void testBoundsOnModeChangeFreeformToFullscreen() {