Improve zoom support to zero in on focal point

forge-gui-mobile/src/forge/screens/match/MatchScreen.java

@@ -3,6 +3,9 @@ package forge.screens.match;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Map.Entry;
+
+import org.apache.commons.lang3.tuple.Pair;
 
 import com.badlogic.gdx.Input.Keys;
 
@@ -15,6 +18,7 @@ import forge.screens.match.views.VDevMenu;
 import forge.screens.match.views.VGameMenu;
 import forge.screens.match.views.VLog;
 import forge.screens.match.views.VPlayerPanel;
+import forge.screens.match.views.VPlayerPanel.InfoTab;
 import forge.screens.match.views.VPlayers;
 import forge.screens.match.views.VPrompt;
 import forge.screens.match.views.VStack;
@@ -226,18 +230,48 @@ public class MatchScreen extends FScreen {
 
         @Override
         public boolean zoom(float x, float y, float amount) {
+            //adjust position for current scroll positions
+            float oldScrollHeight = getScrollHeight();
             y += getScrollTop();
-            float yRatioBefore = (y + getScrollTop()) / getScrollHeight();
+
+            //build map of all horizontal scroll panes and their current scrollWidths and adjusted X values
+            Map<FScrollPane, Pair<Float, Float>> horzScrollPanes = new HashMap<FScrollPane, Pair<Float, Float>>();
+            backupHorzScrollPanes(topPlayerPanel, x, horzScrollPanes);
+            backupHorzScrollPanes(bottomPlayerPanel, x, horzScrollPanes);
 
             extraHeight += amount;
             if (extraHeight < 0) {
                 extraHeight = 0;
             }
-            revalidate();
+            revalidate(); //apply change in height to all scroll panes
 
-            float yRatioAfter = (y + getScrollTop()) / getScrollHeight();
+            //adjust scroll top to keep y position the same
+            float newScrollHeight = getScrollHeight();
+            float yAfter = y * newScrollHeight / oldScrollHeight;
+            setScrollTop(getScrollTop() + yAfter - y);
+
+            //adjust scroll left of all horizontal scroll panes to keep x position the same
+            for (Entry<FScrollPane, Pair<Float, Float>> entry : horzScrollPanes.entrySet()) {
+                FScrollPane horzScrollPane = entry.getKey();
+                x = entry.getValue().getRight();
+                float oldScrollWidth = entry.getValue().getLeft();
+                float newScrollWidth = horzScrollPane.getScrollWidth();
+                float xAfter = x * newScrollWidth / oldScrollWidth;
+                horzScrollPane.setScrollLeft(horzScrollPane.getScrollLeft() + xAfter - x);
+            }
 
             return true;
         }
+
+        private void backupHorzScrollPanes(VPlayerPanel playerPanel, float x, Map<FScrollPane, Pair<Float, Float>> horzScrollPanes) {
+            backupHorzScrollPane(playerPanel.getField().getRow1(), x, horzScrollPanes);
+            backupHorzScrollPane(playerPanel.getField().getRow2(), x, horzScrollPanes);
+            for (InfoTab tab : playerPanel.getTabs()) {
+                backupHorzScrollPane(tab.getDisplayArea(), x, horzScrollPanes);
+            }
+        }
+        private void backupHorzScrollPane(FScrollPane scrollPane, float x, Map<FScrollPane, Pair<Float, Float>> horzScrollPanes) {
+            horzScrollPanes.put(scrollPane, Pair.of(scrollPane.getScrollWidth(), x + scrollPane.getScrollLeft()));
+        }
     }
 }

forge-gui-mobile/src/forge/screens/match/views/VField.java

@@ -171,6 +171,14 @@ public class VField extends FContainer {
         toPanel.setCard(toPanel.getCard());
     }
 
+    public FieldRow getRow1() {
+        return row1;
+    }
+
+    public FieldRow getRow2() {
+        return row2;
+    }
+
     @Override
     public void clear() {
         row1.clear(); //clear rows instead of removing the rows
@@ -193,7 +201,7 @@ public class VField extends FContainer {
         row2.setBounds(0, y2, width, cardSize);
     }
 
-    private class FieldRow extends VCardDisplayArea {
+    public class FieldRow extends VCardDisplayArea {
         private FieldRow() {
             setVisible(true); //make visible by default unlike other display areas
         }

forge-gui-mobile/src/forge/screens/match/views/VPlayerPanel.java

@@ -73,6 +73,10 @@ public class VPlayerPanel extends FContainer {
         tabs.add(zoneTab);
     }
 
+    public Iterable<InfoTab> getTabs() {
+        return tabs;
+    }
+
     public InfoTab getSelectedTab() {
         return selectedTab;
     }
@@ -239,6 +243,10 @@ public class VPlayerPanel extends FContainer {
             displayArea = displayArea0;
         }
 
+        public VDisplayArea getDisplayArea() {
+            return displayArea;
+        }
+
         @Override
         public boolean tap(float x, float y, int count) {
             if (selectedTab == this) {

forge-gui-mobile/src/forge/toolbox/FScrollPane.java

@@ -261,12 +261,12 @@ public abstract class FScrollPane extends FContainer {
 
     @Override
     public boolean pan(float x, float y, float deltaX, float deltaY, boolean moreVertical) {
-        if (getMaxScrollTop() == 0 && (moreVertical || y < 0 || y >= getHeight() || Math.abs(deltaY) > Math.abs(deltaX))) {
+        if (getMaxScrollTop() <= 0 && (moreVertical || y < 0 || y >= getHeight() || Math.abs(deltaY) > Math.abs(deltaX))) {
             //if can't scroll vertically, don't scroll at all if pan is more vertical
             //or current position is above or below this scroll pane
             return false;
         }
-        if (getMaxScrollLeft() == 0 && (!moreVertical || x < 0 || x >= getWidth() || Math.abs(deltaX) > Math.abs(deltaY))) {
+        if (getMaxScrollLeft() <= 0 && (!moreVertical || x < 0 || x >= getWidth() || Math.abs(deltaX) > Math.abs(deltaY))) {
             //if can't scroll horizontally, don't scroll at all if pan is more horizontal
             //or current position is left or right of this scroll pane
             return false;