Added back/forward icon enable/disabling on tablet devices

app/src/main/java/acr/browser/lightning/activity/BrowserActivity.java

@@ -179,6 +179,7 @@ public abstract class BrowserActivity extends ThemableBrowserActivity implements
     private int mOriginalOrientation;
     private int mBackgroundColor;
     private int mIconColor;
+    private int mDisabledIconColor;
     private int mCurrentUiColor = Color.BLACK;
     private String mSearchText;
     private String mUntitledTitle;
@@ -258,6 +259,8 @@ public abstract class BrowserActivity extends ThemableBrowserActivity implements
         //TODO make sure dark theme flag gets set correctly
         mDarkTheme = mPreferences.getUseTheme() != 0 || isIncognito();
         mIconColor = mDarkTheme ? ThemeUtils.getIconDarkThemeColor(this) : ThemeUtils.getIconLightThemeColor(this);
+        mDisabledIconColor = mDarkTheme ? ContextCompat.getColor(this, R.color.icon_dark_theme_disabled) :
+                ContextCompat.getColor(this, R.color.icon_light_theme_disabled);
         mShowTabsInDrawer = mPreferences.getShowTabsInDrawer(!isTablet());
 
         // initialize background ColorDrawable
@@ -1360,14 +1363,45 @@ public abstract class BrowserActivity extends ThemableBrowserActivity implements
         mDrawerLayout.closeDrawers();
     }
 
+    @Override
+    public void setForwardButtonEnabled(boolean enabled) {
+        if (mForwardMenuItem != null && mForwardMenuItem.getIcon() != null) {
+            int colorFilter;
+            if (enabled) {
+                colorFilter = mIconColor;
+            } else {
+                colorFilter = mDisabledIconColor;
+            }
+            mForwardMenuItem.getIcon().setColorFilter(colorFilter, PorterDuff.Mode.SRC_IN);
+            mForwardMenuItem.setIcon(mForwardMenuItem.getIcon());
+        }
+    }
+
+    @Override
+    public void setBackButtonEnabled(boolean enabled) {
+        if (mBackMenuItem != null && mBackMenuItem.getIcon() != null) {
+            int colorFilter;
+            if (enabled) {
+                colorFilter = mIconColor;
+            } else {
+                colorFilter = mDisabledIconColor;
+            }
+            mBackMenuItem.getIcon().setColorFilter(colorFilter, PorterDuff.Mode.SRC_IN);
+            mBackMenuItem.setIcon(mBackMenuItem.getIcon());
+        }
+    }
+
+    private MenuItem mBackMenuItem;
+    private MenuItem mForwardMenuItem;
+
     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
-        MenuItem back = menu.findItem(R.id.action_back);
-        MenuItem forward = menu.findItem(R.id.action_forward);
-        if (back != null && back.getIcon() != null)
-            back.getIcon().setColorFilter(mIconColor, PorterDuff.Mode.SRC_IN);
-        if (forward != null && forward.getIcon() != null)
-            forward.getIcon().setColorFilter(mIconColor, PorterDuff.Mode.SRC_IN);
+        mBackMenuItem = menu.findItem(R.id.action_back);
+        mForwardMenuItem = menu.findItem(R.id.action_forward);
+        if (mBackMenuItem != null && mBackMenuItem.getIcon() != null)
+            mBackMenuItem.getIcon().setColorFilter(mIconColor, PorterDuff.Mode.SRC_IN);
+        if (mForwardMenuItem != null && mForwardMenuItem.getIcon() != null)
+            mForwardMenuItem.getIcon().setColorFilter(mIconColor, PorterDuff.Mode.SRC_IN);
         return super.onCreateOptionsMenu(menu);
     }
 

app/src/main/java/acr/browser/lightning/browser/BrowserPresenter.java

@@ -91,6 +91,8 @@ public class BrowserPresenter {
                 newTab.resumeTimers();
                 newTab.setForegroundTab(true);
                 mView.updateProgress(newTab.getProgress());
+                mView.setBackButtonEnabled(newTab.canGoBack());
+                mView.setForwardButtonEnabled(newTab.canGoForward());
                 mView.updateUrl(newTab.getUrl(), true);
                 mView.setTabView(newTab.getWebView());
             }

app/src/main/java/acr/browser/lightning/browser/BrowserView.java

@@ -25,4 +25,8 @@ public interface BrowserView {
 
     void showSnackbar(@StringRes int resource);
 
+    void setForwardButtonEnabled(boolean enabled);
+
+    void setBackButtonEnabled(boolean enabled);
+
 }

app/src/main/java/acr/browser/lightning/controller/UIController.java

@@ -55,4 +55,8 @@ public interface UIController {
 
     void newTabClicked();
 
+    void setForwardButtonEnabled(boolean enabled);
+
+    void setBackButtonEnabled(boolean enabled);
+
 }

app/src/main/java/acr/browser/lightning/view/LightningWebClient.java

@@ -97,6 +97,8 @@ public class LightningWebClient extends WebViewClient {
     public void onPageFinished(@NonNull WebView view, String url) {
         if (view.isShown()) {
             mUIController.updateUrl(url, true);
+            mUIController.setBackButtonEnabled(view.canGoBack());
+            mUIController.setForwardButtonEnabled(view.canGoForward());
             view.postInvalidate();
         }
         if (view.getTitle() == null || view.getTitle().isEmpty()) {

app/src/main/res/values/colors.xml

@@ -32,6 +32,8 @@
 
     <color name="icon_light_theme">#8A000000</color>
     <color name="icon_dark_theme">#FFFFFFFF</color>
+    <color name="icon_light_theme_disabled">#40000000</color>
+    <color name="icon_dark_theme_disabled">#8AFFFFFF</color>
 
     <color name="error_red">#F44336</color>