#include "base/logging.h"

void NativeWindowWin::UpdateWindowAttribute(int attribute_index,

int attribute_value_to_set,

int attribute_value_to_reset,

bool update_frame) {

HWND native_window = window_->GetNativeWindow();

int value = ::GetWindowLong(native_window, attribute_index);

int expected_value = value;

if (attribute_value_to_set)

expected_value |= attribute_value_to_set;

if (attribute_value_to_reset)

expected_value &= ~attribute_value_to_reset;

if (value != expected_value)

::SetWindowLong(native_window, attribute_index, expected_value);

// Per MSDN, if any of the frame styles is changed, SetWindowPos with the

// SWP_FRAMECHANGED flag must be called in order for the cached window data

// to be updated properly.

// http://msdn.microsoft.com/en-us/library/windows/desktop/ms633591(v=vs.85).aspx

if (update_frame) {

::SetWindowPos(native_window, NULL, 0, 0, 0, 0,

SWP_FRAMECHANGED | SWP_NOMOVE | SWP_NOSIZE |

SWP_NOZORDER | SWP_NOACTIVATE);

}

}

if (!this->has_frame()) {

// An overlapped window is a top-level window that has a titlebar, border,

// and client area. The Windows system will automatically put the shadow

// around the whole window. Also the system will enforce the minimum height

// (38 pixels based on observation) for the overlapped window such that it

// will always has the space for the titlebar.

//

// On contrast, a popup window is a bare minimum window without border and

// titlebar by default. It is often used for the popup menu and the window

// with short life. The Windows system does not add the shadow around the

// whole window though CS_DROPSHADOW class style could be passed to add the

// drop shadow which is only around the right and bottom edges.

//

// The height of the title-only or minimized panel is smaller than the minimum

// overlapped window height. If the panel still uses the overlapped window

// style, Windows system will automatically increase the window height. To

// work around this limitation, we temporarily change the window style to

// popup when the height to set is smaller than the minimum overlapped window

// height and then restore the window style to overlapped when the height

// grows.

static const int kMinimumOverlappedWindowHeight = 38;

gfx::Rect old_bounds = GetWidget()->GetRestoredBounds();

gfx::Rect new_bounds(size);

if (old_bounds.height() > kMinimumOverlappedWindowHeight &&

new_bounds.height() <= kMinimumOverlappedWindowHeight) {

// When the panel height shrinks below the minimum overlapped window height,

// change the window style to popup such that we can show the title-only

// and minimized panel without additional height being added by the system.

UpdateWindowAttribute(GWL_STYLE,

WS_POPUP,

WS_OVERLAPPED | WS_THICKFRAME | WS_SYSMENU,

true);

} else if (old_bounds.height() <= kMinimumOverlappedWindowHeight &&

new_bounds.height() > kMinimumOverlappedWindowHeight) {

// Change the window style back to overlappped when the panel height grow

// taller than the minimum overlapped window height.

UpdateWindowAttribute(GWL_STYLE,

WS_OVERLAPPED | WS_THICKFRAME | WS_SYSMENU,

WS_POPUP,

true);

}

}

// Sets |attribute_value_to_set| and/or clears |attribute_value_to_reset| for

// the attibute denoted by |attribute_index|. This is used to update the style

// or extended style for the native window.

void UpdateWindowAttribute(int attribute_index,

int attribute_value_to_set,

int attribute_value_to_reset,

bool update_frame);