1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
3 /* This Source Code Form is subject to the terms of the Mozilla Public
4  * License, v. 2.0. If a copy of the MPL was not distributed with this
5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 
7 #ifndef MOZILLA_PAINTING_MATRIXSTACK_H
8 #define MOZILLA_PAINTING_MATRIXSTACK_H
9 
10 #include "nsTArray.h"
11 #include "mozilla/gfx/MatrixFwd.h"
12 
13 namespace mozilla {
14 
15 /**
16  * MatrixStack stores a stack of matrices and keeps track of the accumulated
17  * transform matrix.
18  */
19 template <typename T>
20 class MatrixStack {
21  public:
22   MatrixStack() = default;
23 
~MatrixStack()24   ~MatrixStack() { MOZ_ASSERT(mMatrices.IsEmpty()); }
25 
26   /**
27    * Returns the current accumulated transform matrix.
28    */
CurrentMatrix()29   const T& CurrentMatrix() const { return mCurrentMatrix; }
30 
31   /**
32    * Returns true if any matrices are currently pushed to the stack.
33    */
HasTransform()34   bool HasTransform() const { return mMatrices.Length() > 0; }
35 
36   /**
37    * Pushes the given |aMatrix| to the stack.
38    */
Push(const T & aMatrix)39   void Push(const T& aMatrix) {
40     mMatrices.AppendElement(mCurrentMatrix);
41     mCurrentMatrix = aMatrix * mCurrentMatrix;
42   }
43 
44   /**
45    * Pops the most recently added matrix from the stack.
46    */
Pop()47   void Pop() {
48     MOZ_ASSERT(mMatrices.Length() > 0);
49     mCurrentMatrix = mMatrices.PopLastElement();
50   }
51 
52  private:
53   T mCurrentMatrix;
54   AutoTArray<T, 2> mMatrices;
55 };
56 
57 typedef MatrixStack<gfx::Matrix4x4Flagged> MatrixStack4x4;
58 
59 }  // namespace mozilla
60 
61 #endif /* MOZILLA_PAINTING_MATRIXSTACK_H */
62