Merge pull request #5931 from Dhilan007/develop_label

label: Support to clip transparent area of Label, content size will be updated with only non-transparent area.

cocos/2d/CCFontAtlas.cpp

@@ -231,6 +231,8 @@ bool FontAtlas::prepareLetterDefinitions(unsigned short *utf16String)
     auto  pixelFormat = fontTTf->getOutlineSize() > 0 ? Texture2D::PixelFormat::AI88 : Texture2D::PixelFormat::A8; 
 
     bool existNewLetter = false;
+    int bottomHeight = _commonLineHeight - _fontAscender;
+
     for (int i = 0; i < length; ++i)
     {
         auto outIterator = _fontLetterDefinitions.find(utf16String[i]);
@@ -248,6 +250,7 @@ bool FontAtlas::prepareLetterDefinitions(unsigned short *utf16String)
                 tempDef.height           = tempRect.size.height + _letterPadding;
                 tempDef.offsetX          = tempRect.origin.x + offsetAdjust;
                 tempDef.offsetY          = _fontAscender + tempRect.origin.y - offsetAdjust;
+                tempDef.clipBottom     = bottomHeight - (tempDef.height + tempRect.origin.y + offsetAdjust);
 
                 if (_currentPageOrigX + tempDef.width > CacheTextureWidth)
                 {
@@ -290,6 +293,7 @@ bool FontAtlas::prepareLetterDefinitions(unsigned short *utf16String)
                 tempDef.offsetX          = 0;
                 tempDef.offsetY          = 0;
                 tempDef.textureID        = 0;
+                tempDef.clipBottom = 0;
                 _currentPageOrigX += 1;
             }
 

cocos/2d/CCFontAtlas.h

@@ -50,6 +50,8 @@ struct FontLetterDefinition
     int textureID;
     bool validDefinition;
     int xAdvance;
+
+    int clipBottom;
 };
 
 class CC_DLL FontAtlas : public Ref

cocos/2d/CCLabel.cpp

@@ -340,6 +340,8 @@ void Label::reset()
     _textColor = Color4B::WHITE;
     _textColorF = Color4F::WHITE;
     setColor(Color3B::WHITE);
+
+    _clipEnabled = false;
 }
 
 void Label::updateShaderProgram()

cocos/2d/CCLabel.h

@@ -217,6 +217,10 @@ public:
 
     virtual Sprite * getLetter(int lettetIndex);
 
+    /** clip upper and lower margin for reduce height of label.
+     */
+    void setClipMarginEnabled(bool clipEnabled) { _clipEnabled = clipEnabled; }
+    bool isClipMarginEnabled() const { return _clipEnabled; }
     // font related stuff
     int getCommonLineHeight() const;
     
@@ -365,6 +369,8 @@ protected:
     Color4B _textColor;
     Color4F _textColorF;
 
+    bool _clipEnabled;
+
 private:
     CC_DISALLOW_COPY_AND_ASSIGN(Label);
 

cocos/2d/CCLabelTextFormatter.cpp

@@ -321,6 +321,16 @@ bool LabelTextFormatter::createStringSprites(Label *theLabel)
     FontLetterDefinition tempDefinition;
     Point letterPosition;
     const auto& kernings = theLabel->_horizontalKernings;
+
+    float clipTop = 0;
+    float clipBottom = 0;
+    int lineIndex = 0;
+    bool lineStart = true;
+    bool clip = false;
+    if (theLabel->_currentLabelType == Label::LabelType::TTF && theLabel->_clipEnabled)
+    {
+        clip = true;
+    }
     
     for (unsigned int i = 0; i < stringLen; i++)
     {
@@ -337,9 +347,10 @@ bool LabelTextFormatter::createStringSprites(Label *theLabel)
             charYOffset         = -1;
             charAdvance         = -1;
         }
-        
+
         if (c == '\n')
         {
+            lineIndex++;
             nextFontPositionX  = 0;
             nextFontPositionY -= theLabel->_commonLineHeight;
             
@@ -347,8 +358,30 @@ bool LabelTextFormatter::createStringSprites(Label *theLabel)
             if(nextFontPositionY < theLabel->_commonLineHeight)
                 break;
 
+            lineStart = true;
             continue;     
         }
+        else if (clip && tempDefinition.height > 0.0f)
+        {
+            if (lineStart)
+            {
+                if (lineIndex == 0)
+                {
+                    clipTop = charYOffset;
+                }
+                lineStart = false;
+                clipBottom = tempDefinition.clipBottom;
+            }
+            else if(tempDefinition.clipBottom < clipBottom)
+            {
+                clipBottom = tempDefinition.clipBottom;
+            }
+
+            if (lineIndex == 0 && charYOffset < clipTop)
+            {
+                clipTop = charYOffset;
+            }
+        }
         
         letterPosition.x = (nextFontPositionX + charXOffset + kernings[i]) / contentScaleFactor;
         letterPosition.y = (nextFontPositionY - charYOffset) / contentScaleFactor;
@@ -382,11 +415,26 @@ bool LabelTextFormatter::createStringSprites(Label *theLabel)
     }
     
     tmpSize.height = totalHeight;
+    
     if (theLabel->_labelHeight > 0)
     {
         tmpSize.height = theLabel->_labelHeight * contentScaleFactor;
     }
+
+    if (clip)
+    {
+        int clipTotal = (clipTop + clipBottom) / contentScaleFactor;
+        tmpSize.height -= clipTotal * contentScaleFactor;
+        clipBottom /= contentScaleFactor;
+
+        for (int i = 0; i < theLabel->_limitShowCount; i++)
+        {
+            theLabel->_lettersInfo[i].position.y -= clipBottom;
+        }
+    }
+    
     theLabel->setContentSize(CC_SIZE_PIXELS_TO_POINTS(tmpSize));
+
     return true;
 }