1 /* 2 * Copyright 2017 Google Inc. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef LIB_TXT_SRC_PARAGRAPH_BUILDER_H_ 18 #define LIB_TXT_SRC_PARAGRAPH_BUILDER_H_ 19 20 #include <memory> 21 #include <string> 22 23 #include "flutter/fml/macros.h" 24 #include "font_collection.h" 25 #include "paragraph.h" 26 #include "paragraph_style.h" 27 #include "placeholder_run.h" 28 #include "text_style.h" 29 30 namespace txt { 31 32 class ParagraphBuilder { 33 public: 34 static std::unique_ptr<ParagraphBuilder> CreateTxtBuilder( 35 const ParagraphStyle& style, 36 std::shared_ptr<FontCollection> font_collection); 37 38 #if FLUTTER_ENABLE_SKSHAPER 39 static std::unique_ptr<ParagraphBuilder> CreateSkiaBuilder( 40 const ParagraphStyle& style, 41 std::shared_ptr<FontCollection> font_collection); 42 #endif 43 44 virtual ~ParagraphBuilder() = default; 45 46 // Push a style to the stack. The corresponding text added with AddText will 47 // use the top-most style. 48 virtual void PushStyle(const TextStyle& style) = 0; 49 50 // Remove a style from the stack. Useful to apply different styles to chunks 51 // of text such as bolding. 52 // Example: 53 // builder.PushStyle(normal_style); 54 // builder.AddText("Hello this is normal. "); 55 // 56 // builder.PushStyle(bold_style); 57 // builder.AddText("And this is BOLD. "); 58 // 59 // builder.Pop(); 60 // builder.AddText(" Back to normal again."); 61 virtual void Pop() = 0; 62 63 // Returns the last TextStyle on the stack. 64 virtual const TextStyle& PeekStyle() = 0; 65 66 // Adds text to the builder. Forms the proper runs to use the upper-most style 67 // on the style_stack_; 68 virtual void AddText(const std::u16string& text) = 0; 69 70 // Pushes the information requried to leave an open space, where Flutter may 71 // draw a custom placeholder into. 72 // 73 // Internally, this method adds a single object replacement character (0xFFFC) 74 // and emplaces a new PlaceholderRun instance to the vector of inline 75 // placeholders. 76 virtual void AddPlaceholder(PlaceholderRun& span) = 0; 77 78 // Constructs a Paragraph object that can be used to layout and paint the text 79 // to a SkCanvas. 80 virtual std::unique_ptr<Paragraph> Build() = 0; 81 82 protected: 83 ParagraphBuilder() = default; 84 85 private: 86 FML_DISALLOW_COPY_AND_ASSIGN(ParagraphBuilder); 87 }; 88 89 } // namespace txt 90 91 #endif // LIB_TXT_SRC_PARAGRAPH_BUILDER_H_ 92