1 
2 /*
3  * Copyright 2011 Google Inc.
4  *
5  * Use of this source code is governed by a BSD-style license that can be
6  * found in the LICENSE file.
7  */
8 #ifndef SkTouchGesture_DEFINED
9 #define SkTouchGesture_DEFINED
10 
11 #include "../private/SkTDArray.h"
12 #include "SkMatrix.h"
13 
14 struct SkFlingState {
SkFlingStateSkFlingState15     SkFlingState() : fActive(false) {}
16 
isActiveSkFlingState17     bool isActive() const { return fActive; }
stopSkFlingState18     void stop() { fActive = false; }
19 
20     void reset(float sx, float sy);
21     bool evaluateMatrix(SkMatrix* matrix);
22 
23 private:
24     SkPoint     fDirection;
25     SkScalar    fSpeed0;
26     double      fTime0;
27     bool        fActive;
28 };
29 
30 class SkTouchGesture {
31 public:
32     SkTouchGesture();
33     ~SkTouchGesture();
34 
35     void touchBegin(void* owner, float x, float y);
36     void touchMoved(void* owner, float x, float y);
37     void touchEnd(void* owner);
38     void reset();
39 
isActive()40     bool isActive() { return fFlinger.isActive(); }
stop()41     void stop() { fFlinger.stop(); }
42 
43     const SkMatrix& localM();
globalM()44     const SkMatrix& globalM() const { return fGlobalM; }
45 
46     void setTransLimit(const SkRect& contentRect, const SkRect& windowRect);
47 
48 private:
49     enum State {
50         kEmpty_State,
51         kTranslate_State,
52         kZoom_State,
53     };
54 
55     struct Rec {
56         void*   fOwner;
57         float   fStartX, fStartY;
58         float   fPrevX, fPrevY;
59         float   fLastX, fLastY;
60         float   fPrevT, fLastT;
61     };
62     SkTDArray<Rec> fTouches;
63 
64     State           fState;
65     SkMatrix        fLocalM, fGlobalM;
66     SkFlingState    fFlinger;
67     double          fLastUpMillis;
68     SkPoint         fLastUpP;
69 
70     // The following rects are used to limit the translation so the content never leaves the window
71     SkRect          fContentRect, fWindowRect;
72     bool            fIsTransLimited = false;
73 
74     void limitTrans(); // here we only limit the translation with respect to globalM
75     void flushLocalM();
76     int findRec(void* owner) const;
77     void appendNewRec(void* owner, float x, float y);
78     float computePinch(const Rec&, const Rec&);
79     float limitTotalZoom(float scale) const;
80     bool handleDblTap(float, float);
81 };
82 
83 #endif
84