70 lines
2.3 KiB
Go
70 lines
2.3 KiB
Go
// 4 august 2014
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package ui
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// #include "winapi_windows.h"
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import "C"
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type sizing struct {
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sizingbase
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// for size calculations
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baseX C.int
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baseY C.int
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internalLeading C.LONG // for Label; see Label.commitResize() for details
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// for the actual resizing
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// possibly the HDWP
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}
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// For Windows, Microsoft just hands you a list of preferred control sizes as part of the MSDN documentation and tells you to roll with it.
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// These sizes are given in "dialog units", which are independent of the font in use.
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// We need to convert these into standard pixels, which requires we get the device context of the OS window.
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// References:
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// - http://msdn.microsoft.com/en-us/library/ms645502%28VS.85%29.aspx - the calculation needed
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// - http://support.microsoft.com/kb/125681 - to get the base X and Y
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// (thanks to http://stackoverflow.com/questions/58620/default-button-size)
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// In my tests (see https://github.com/andlabs/windlgunits), the GetTextExtentPoint32() option for getting the base X produces much more accurate results than the tmAveCharWidth option when tested against the sample values given in http://msdn.microsoft.com/en-us/library/windows/desktop/dn742486.aspx#sizingandspacing, but can be off by a pixel in either direction (probably due to rounding errors).
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// note on MulDiv():
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// div will not be 0 in the usages below
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// we also ignore overflow; that isn't likely to happen for our use case anytime soon
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func fromdlgunitsX(du int, d *sizing) int {
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return int(C.MulDiv(C.int(du), d.baseX, 4))
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}
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func fromdlgunitsY(du int, d *sizing) int {
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return int(C.MulDiv(C.int(du), d.baseY, 8))
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}
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const (
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// shared by multiple containers
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marginDialogUnits = 7
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paddingDialogUnits = 4
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)
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func beginResize(hwnd C.HWND) (d *sizing) {
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var baseX, baseY C.int
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var internalLeading C.LONG
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d = new(sizing)
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C.calculateBaseUnits(hwnd, &baseX, &baseY, &internalLeading)
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d.baseX = baseX
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d.baseY = baseY
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d.internalLeading = internalLeading
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d.xpadding = fromdlgunitsX(paddingDialogUnits, d)
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d.ypadding = fromdlgunitsY(paddingDialogUnits, d)
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return d
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}
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func marginRectDLU(r *C.RECT, top int, bottom int, left int, right int, d *sizing) {
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r.left += C.LONG(fromdlgunitsX(left, d))
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r.top += C.LONG(fromdlgunitsY(top, d))
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r.right -= C.LONG(fromdlgunitsX(right, d))
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r.bottom -= C.LONG(fromdlgunitsY(bottom, d))
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}
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