layout/painting/MatrixStack.h

   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
  24   ~MatrixStack() { MOZ_ASSERT(mMatrices.IsEmpty()); }
  25
  26   /**
  27    * Returns the current accumulated transform matrix.
  28    */
  29   const T& CurrentMatrix() const { return mCurrentMatrix; }
  30
  31   /**
  32    * Returns true if any matrices are currently pushed to the stack.
  33    */
  34   bool HasTransform() const { return mMatrices.Length() > 0; }
  35
  36   /**
  37    * Pushes the given |aMatrix| to the stack.
  38    */
  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    */
  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 */