src/servers/app/decorator/MagneticBorder.cpp

   1 /*
   2  * Copyright 2010-2011, Haiku, Inc.
   3  * Distributed under the terms of the MIT license.
   4  *
   5  * Authors:
   6  *              Stephan Aßmus <superstippi@gmx.de>
   7  *              Ingo Weinhold <ingo_weinhold@gmx.de>
   8  *              Clemens Zeidler <haiku@clemens-zeidler.de>
   9  */
  10
  11
  12 #include "MagneticBorder.h"
  13
  14 #include "Decorator.h"
  15 #include "Window.h"
  16 #include "Screen.h"
  17
  18
  19 MagneticBorder::MagneticBorder()
  20         :
  21         fLastSnapTime(0)
  22 {
  23
  24 }
  25
  26
  27 bool
  28 MagneticBorder::AlterDeltaForSnap(Window* window, BPoint& delta, bigtime_t now)
  29 {
  30         BRect frame = window->Frame();
  31         Decorator* decorator = window->Decorator();
  32         if (decorator)
  33                 frame = decorator->GetFootprint().Frame();
  34
  35         return AlterDeltaForSnap(window->Screen(), frame, delta, now);
  36 }
  37
  38
  39 bool
  40 MagneticBorder::AlterDeltaForSnap(const Screen* screen, BRect& frame,
  41         BPoint& delta, bigtime_t now)
  42 {
  43         // Alter the delta (which is a proposed offset used while dragging a
  44         // window) so that the frame of the window 'snaps' to the edges of the
  45         // screen.
  46
  47         const bigtime_t kSnappingDuration = 1500000LL;
  48         const bigtime_t kSnappingPause = 3000000LL;
  49         const float kSnapDistance = 8.0f;
  50
  51         if (now - fLastSnapTime > kSnappingDuration
  52                 && now - fLastSnapTime < kSnappingPause) {
  53                 // Maintain a pause between snapping.
  54                 return false;
  55         }
  56
  57         // TODO: Perhaps obtain the usable area (not covered by the Deskbar)?
  58         BRect screenFrame = screen->Frame();
  59         BRect originalFrame = frame;
  60         frame.OffsetBy(delta);
  61
  62         float leftDist = fabs(frame.left - screenFrame.left);
  63         float topDist = fabs(frame.top - screenFrame.top);
  64         float rightDist = fabs(frame.right - screenFrame.right);
  65         float bottomDist = fabs(frame.bottom - screenFrame.bottom);
  66
  67         bool snapped = false;
  68         if (leftDist < kSnapDistance || rightDist < kSnapDistance) {
  69                 snapped = true;
  70                 if (leftDist < rightDist)
  71                         delta.x = screenFrame.left - originalFrame.left;
  72                 else
  73                         delta.x = screenFrame.right - originalFrame.right;
  74         }
  75
  76         if (topDist < kSnapDistance || bottomDist < kSnapDistance) {
  77                 snapped = true;
  78                 if (topDist < bottomDist)
  79                         delta.y = screenFrame.top - originalFrame.top;
  80                 else
  81                         delta.y = screenFrame.bottom - originalFrame.bottom;
  82         }
  83         if (snapped && now - fLastSnapTime > kSnappingPause)
  84                 fLastSnapTime = now;
  85
  86         return snapped;
  87 }