CharacterMap: select Unicode block for current character

* Scrolling the list of characters now selects the currently visible
block in the blocks list.

Signed-off-by: Adrien Destugues <pulkomandy@gmail.com>

Fixes #3651, part 1

src/apps/charactermap/CharacterView.cpp

@@ -108,6 +108,12 @@ CharacterView::IsShowingBlock(int32 blockIndex) const
 void
 CharacterView::ScrollToBlock(int32 blockIndex)
 {
+	// don't scroll if the selected character is already in view.
+	// this prevents distracting jumps when crossing a block 
+	// boundary in the character view.
+	if (IsCharacterVisible(fCurrentCharacter))
+		return;
+		
 	if (blockIndex < 0)
 		blockIndex = 0;
 	else if (blockIndex >= (int32)kNumUnicodeBlocks)

src/apps/charactermap/CharacterWindow.cpp

@@ -319,6 +319,8 @@ CharacterWindow::MessageReceived(BMessage* message)
 
 			fGlyphView->SetText(glyph);
 			fCodeView->SetText(text);
+			
+			fUnicodeBlockView->SelectBlockForCharacter(character);
 			break;
 		}
 

src/apps/charactermap/UnicodeBlockView.cpp

@@ -118,3 +118,22 @@ UnicodeBlockView::_CreateBlocks()
 	_UpdateBlocks();
 }
 
+
+void
+UnicodeBlockView::SelectBlockForCharacter(uint32 character)
+{
+	// find block containing the character
+
+	// TODO: could use binary search here
+	for (uint32 i = 0; i < kNumUnicodeBlocks; i++) {
+		if (kUnicodeBlocks[i].end < character)
+			continue;
+		if (kUnicodeBlocks[i].start > character) {
+			// Character is not mapped
+			break;
+		}
+
+		Select(i);
+		ScrollToSelection();
+	}
+}

src/apps/charactermap/UnicodeBlockView.h

@@ -40,6 +40,7 @@ public:
 								{ return fShowContainedBlocksOnly; }
 
 			bool			IsShowingBlock(int32 blockIndex) const;
+			void			SelectBlockForCharacter(uint32 character);
 
 private:
 			void			_UpdateBlocks();