andlabs-ui/newctrl/container_windows.go

115 lines
3.2 KiB
Go

// 4 august 2014
package ui
import (
"fmt"
"syscall"
)
// #include "winapi_windows.h"
import "C"
type container struct {
*controlSingleHWND
}
type sizing struct {
sizingbase
// for size calculations
baseX C.int
baseY C.int
internalLeading C.LONG // for Label; see Label.commitResize() for details
// for the actual resizing
// possibly the HDWP
}
func makeContainerWindowClass() error {
var errmsg *C.char
err := C.makeContainerWindowClass(&errmsg)
if err != 0 || errmsg != nil {
return fmt.Errorf("%s: %v", C.GoString(errmsg), syscall.Errno(err))
}
return nil
}
func newContainer() *container {
// don't set preferredSize(); it should never be called
return &container{
controlSingleHWND: newControlSingleHWND(C.newContainer()),
}
}
// TODO merge with controlSingleHWND
func (c *container) show() {
C.ShowWindow(c.hwnd, C.SW_SHOW)
}
// TODO merge with controlSingleHWND
func (c *container) hide() {
C.ShowWindow(c.hwnd, C.SW_HIDE)
}
func (c *container) parent() *controlParent {
return &controlParent{c.hwnd}
}
func (c *container) bounds(d *sizing) (int, int, int, int) {
r := C.containerBounds(c.hwnd)
return int(r.left), int(r.top), int(r.right - r.left), int(r.bottom - r.top)
}
// 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.
// These sizes are given in "dialog units", which are independent of the font in use.
// We need to convert these into standard pixels, which requires we get the device context of the OS window.
// References:
// - http://msdn.microsoft.com/en-us/library/ms645502%28VS.85%29.aspx - the calculation needed
// - http://support.microsoft.com/kb/125681 - to get the base X and Y
// (thanks to http://stackoverflow.com/questions/58620/default-button-size)
// 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).
// note on MulDiv():
// div will not be 0 in the usages below
// we also ignore overflow; that isn't likely to happen for our use case anytime soon
func fromdlgunitsX(du int, d *sizing) int {
return int(C.MulDiv(C.int(du), d.baseX, 4))
}
func fromdlgunitsY(du int, d *sizing) int {
return int(C.MulDiv(C.int(du), d.baseY, 8))
}
const (
// shared by multiple containers
marginDialogUnits = 7
paddingDialogUnits = 4
)
func (w *window) beginResize() (d *sizing) {
var baseX, baseY C.int
var internalLeading C.LONG
d = new(sizing)
C.calculateBaseUnits(w.hwnd, &baseX, &baseY, &internalLeading)
d.baseX = baseX
d.baseY = baseY
d.internalLeading = internalLeading
d.xpadding = fromdlgunitsX(paddingDialogUnits, d)
d.ypadding = fromdlgunitsY(paddingDialogUnits, d)
return d
}
func marginRectDLU(r *C.RECT, top int, bottom int, left int, right int, d *sizing) {
r.left += C.LONG(fromdlgunitsX(left, d))
r.top += C.LONG(fromdlgunitsY(top, d))
r.right -= C.LONG(fromdlgunitsX(right, d))
r.bottom -= C.LONG(fromdlgunitsY(bottom, d))
}