// 24 march 2014

#include "winapi_windows.h"

#include "_cgo_export.h"

static void getScrollPos(HWND hwnd, int *xpos, int *ypos)

{

SCROLLINFO si;

ZeroMemory(&si, sizeof (SCROLLINFO));

si.cbSize = sizeof (SCROLLINFO);

si.fMask = SIF_POS | SIF_TRACKPOS;

if (GetScrollInfo(hwnd, SB_HORZ, &si) == 0)

xpanic("error getting horizontal scroll position for Area", GetLastError());

*xpos = si.nPos;

// MSDN example code reinitializes this each time, so we'll do it too just to be safe

ZeroMemory(&si, sizeof (SCROLLINFO));

si.cbSize = sizeof (SCROLLINFO);

si.fMask = SIF_POS | SIF_TRACKPOS;

if (GetScrollInfo(hwnd, SB_VERT, &si) == 0)

xpanic("error getting vertical scroll position for Area", GetLastError());

*ypos = si.nPos;

}

#define areaBackgroundBrush ((HBRUSH) (COLOR_BTNFACE + 1))

static void paintArea(HWND hwnd, void *data)

{

RECT xrect;

PAINTSTRUCT ps;

HDC hdc;

HDC rdc;

HBITMAP rbitmap, prevrbitmap;

RECT rrect;

BITMAPINFO bi;

VOID *ppvBits;

HBITMAP ibitmap;

HDC idc;

HBITMAP previbitmap;

BLENDFUNCTION blendfunc;

void *i;

intptr_t dx, dy;

int hscroll, vscroll;

// FALSE here indicates don't send WM_ERASEBKGND

if (GetUpdateRect(hwnd, &xrect, FALSE) == 0)

return; // no update rect; do nothing

getScrollPos(hwnd, &hscroll, &vscroll);

hdc = BeginPaint(hwnd, &ps);

if (hdc == NULL)

xpanic("error beginning Area repaint", GetLastError());

// very big thanks to Ninjifox for suggesting this technique and helping me go through it

// first let's create the destination image, which we fill with the windows background color

// this is how we fake drawing the background; see also http://msdn.microsoft.com/en-us/library/ms969905.aspx

rdc = CreateCompatibleDC(hdc);

if (rdc == NULL)

xpanic("error creating off-screen rendering DC", GetLastError());

// the bitmap has to be compatible with the window

// if we create a bitmap compatible with the DC we just created, it'll be monochrome

// thanks to David Heffernan in http://stackoverflow.com/questions/23033636/winapi-gdi-fillrectcolor-btnface-fills-with-strange-grid-like-brush-on-window

rbitmap = CreateCompatibleBitmap(hdc, xrect.right - xrect.left, xrect.bottom - xrect.top);

if (rbitmap == NULL)

xpanic("error creating off-screen rendering bitmap", GetLastError());

prevrbitmap = (HBITMAP) SelectObject(rdc, rbitmap);

if (prevrbitmap == NULL)

xpanic("error connecting off-screen rendering bitmap to off-screen rendering DC", GetLastError());

rrect.left = 0;

rrect.right = xrect.right - xrect.left;

rrect.top = 0;

rrect.bottom = xrect.bottom - xrect.top;

if (FillRect(rdc, &rrect, areaBackgroundBrush) == 0)

xpanic("error filling off-screen rendering bitmap with the system background color", GetLastError());

i = doPaint(&xrect, hscroll, vscroll, data, &dx, &dy);

if (i == NULL) // cliprect empty

goto nobitmap; // we need to blit the background no matter what

// now we need to shove realbits into a bitmap

// technically bitmaps don't know about alpha; they just ignore the alpha byte

// AlphaBlend(), however, sees it - see http://msdn.microsoft.com/en-us/library/windows/desktop/dd183352%28v=vs.85%29.aspx

ZeroMemory(&bi, sizeof (BITMAPINFO));

bi.bmiHeader.biSize = sizeof (BITMAPINFOHEADER);

bi.bmiHeader.biWidth = (LONG) dx;

bi.bmiHeader.biHeight = -((LONG) dy); // negative height to force top-down drawing;

bi.bmiHeader.biPlanes = 1;

bi.bmiHeader.biBitCount = 32;

bi.bmiHeader.biCompression = BI_RGB;

bi.bmiHeader.biSizeImage = (DWORD) (dx * dy * 4);

// this is all we need, but because this confused me at first, I will say the two pixels-per-meter fields are unused (see http://blogs.msdn.com/b/oldnewthing/archive/2013/05/15/10418646.aspx and page 581 of Charles Petzold's Programming Windows, Fifth Edition)

// now for the trouble: CreateDIBSection() allocates the memory for us...

ibitmap = CreateDIBSection(NULL, // Ninjifox does this, so do some wine tests (http://source.winehq.org/source/dlls/gdi32/tests/bitmap.c#L725, thanks vpovirk in irc.freenode.net/#winehackers) and even Raymond Chen (http://blogs.msdn.com/b/oldnewthing/archive/2006/11/16/1086835.aspx), so.

&bi, DIB_RGB_COLORS, &ppvBits, 0, 0);

if (ibitmap == NULL)

xpanic("error creating HBITMAP for image returned by AreaHandler.Paint()", GetLastError());

// now we have to do TWO MORE things before we can finally do alpha blending

// first, we need to load the bitmap memory, because Windows makes it for us

// the pixels are arranged in RGBA order, but GDI requires BGRA

// this turns out to be just ARGB in little endian; let's convert into this memory

dotoARGB(i, (void *) ppvBits, FALSE); // FALSE = not NRGBA

// the second thing is... make a device context for the bitmap :|

// Ninjifox just makes another compatible DC; we'll do the same

idc = CreateCompatibleDC(hdc);

if (idc == NULL)

xpanic("error creating HDC for image returned by AreaHandler.Paint()", GetLastError());

previbitmap = (HBITMAP) SelectObject(idc, ibitmap);

if (previbitmap == NULL)

xpanic("error connecting HBITMAP for image returned by AreaHandler.Paint() to its HDC", GetLastError());

// AND FINALLY WE CAN DO THE ALPHA BLENDING!!!!!!111

blendfunc.BlendOp = AC_SRC_OVER;

blendfunc.BlendFlags = 0;

blendfunc.SourceConstantAlpha = 255; // only use per-pixel alphas

blendfunc.AlphaFormat = AC_SRC_ALPHA; // premultiplied

if (AlphaBlend(rdc, 0, 0, (int) dx, (int) dy, // destination

idc, 0, 0, (int) dx, (int)dy, // source

blendfunc) == FALSE)

xpanic("error alpha-blending image returned by AreaHandler.Paint() onto background", GetLastError());

// clean up after idc/ibitmap here because of the goto nobitmap

if (SelectObject(idc, previbitmap) != ibitmap)

xpanic("error reverting HDC for image returned by AreaHandler.Paint() to original HBITMAP", GetLastError());

if (DeleteObject(ibitmap) == 0)

xpanic("error deleting HBITMAP for image returned by AreaHandler.Paint()", GetLastError());

if (DeleteDC(idc) == 0)

xpanic("error deleting HDC for image returned by AreaHandler.Paint()", GetLastError());

nobitmap:

// and finally we can just blit that into the window

if (BitBlt(hdc, xrect.left, xrect.top, xrect.right - xrect.left, xrect.bottom - xrect.top,

rdc, 0, 0, // from the rdc's origin

SRCCOPY) == 0)

xpanic("error blitting Area image to Area", GetLastError());

// now to clean up

if (SelectObject(rdc, prevrbitmap) != rbitmap)

xpanic("error reverting HDC for off-screen rendering to original HBITMAP", GetLastError());

if (DeleteObject(rbitmap) == 0)

xpanic("error deleting HBITMAP for off-screen rendering", GetLastError());

if (DeleteDC(rdc) == 0)

xpanic("error deleting HDC for off-screen rendering", GetLastError());

EndPaint(hwnd, &ps);

}

static SIZE getAreaControlSize(HWND hwnd)

{

RECT rect;

SIZE size;

if (GetClientRect(hwnd, &rect) == 0)

xpanic("error getting size of actual Area control", GetLastError());

size.cx = (LONG) (rect.right - rect.left);

size.cy = (LONG) (rect.bottom - rect.top);

return size;

}

static void scrollArea(HWND hwnd, void *data, WPARAM wParam, int which)

{

SCROLLINFO si;

SIZE size;

LONG cwid, cht;

LONG pagesize, maxsize;

LONG newpos;

LONG delta;

LONG dx, dy;

size = getAreaControlSize(hwnd);

cwid = size.cx;

cht = size.cy;

if (which == SB_HORZ) {

pagesize = cwid;

maxsize = areaWidthLONG(data);

} else if (which == SB_VERT) {

pagesize = cht;

maxsize = areaHeightLONG(data);

} else

xpanic("invalid which sent to scrollArea()", 0);

ZeroMemory(&si, sizeof (SCROLLINFO));

si.cbSize = sizeof (SCROLLINFO);

si.fMask = SIF_POS | SIF_TRACKPOS;

if (GetScrollInfo(hwnd, which, &si) == 0)

xpanic("error getting current scroll position for scrolling", GetLastError());

newpos = (LONG) si.nPos;

switch (LOWORD(wParam)) {

case SB_LEFT: // also SB_TOP; C won't let me have both (C89 §6.6.4.2; C99 §6.8.4.2)

newpos = 0;

break;

case SB_RIGHT: // also SB_BOTTOM

// see comment in adjustAreaScrollbars() below

newpos = maxsize - pagesize;

break;

case SB_LINELEFT: // also SB_LINEUP

newpos--;

break;

case SB_LINERIGHT: // also SB_LINEDOWN

newpos++;

break;

case SB_PAGELEFT: // also SB_PAGEUP

newpos -= pagesize;

break;

case SB_PAGERIGHT: // also SB_PAGEDOWN

newpos += pagesize;

break;

case SB_THUMBPOSITION:

// raymond chen says to just set the newpos to the SCROLLINFO nPos for this message; see http://blogs.msdn.com/b/oldnewthing/archive/2003/07/31/54601.aspx and http://blogs.msdn.com/b/oldnewthing/archive/2003/08/05/54602.aspx

// do nothing here; newpos already has nPos

break;

case SB_THUMBTRACK:

newpos = (LONG) si.nTrackPos;

}

// otherwise just keep the current position (that's what MSDN example code says, anyway)

// make sure we're not out of range

if (newpos < 0)

newpos = 0;

if (newpos > (maxsize - pagesize))

newpos = maxsize - pagesize;

// this would be where we would put a check to not scroll if the scroll position changed, but see the note about SB_THUMBPOSITION above: Raymond Chen's code always does the scrolling anyway in this case

delta = -(newpos - si.nPos); // negative because ScrollWindowEx() scrolls in the opposite direction

dx = delta;

dy = 0;

if (which == SB_VERT) {

dx = 0;

dy = delta;

}

// this automatically scrolls the edit control, if any

if (ScrollWindowEx(hwnd,

(int) dx, (int) dy,

// these four change what is scrolled and record info about the scroll; we're scrolling the whole client area and don't care about the returned information here

NULL, NULL, NULL, NULL,

// mark the remaining rect as needing redraw and erase...

SW_INVALIDATE | SW_ERASE) == ERROR)

xpanic("error scrolling Area", GetLastError());

// ...but don't redraw the window yet; we need to apply our scroll changes

// we actually have to commit the change back to the scrollbar; otherwise the scroll position will merely reset itself

ZeroMemory(&si, sizeof (SCROLLINFO));

si.cbSize = sizeof (SCROLLINFO);

si.fMask = SIF_POS;

si.nPos = (int) newpos;

// this is not expressly documented as returning an error so IDK what the error code is so assume there is none

SetScrollInfo(hwnd, which, &si, TRUE); // redraw scrollbar

// NOW redraw it

if (UpdateWindow(hwnd) == 0)

xpanic("error updating Area after scrolling", GetLastError());

if ((HWND) GetWindowLongPtrW(hwnd, 0) != NULL)

if (UpdateWindow((HWND) GetWindowLongPtrW(hwnd, 0)) == 0)

xpanic("error updating Area TextField after scrolling", GetLastError());

}

static void adjustAreaScrollbars(HWND hwnd, void *data)

{

SCROLLINFO si;

SIZE size;

LONG cwid, cht;

size = getAreaControlSize(hwnd);

cwid = size.cx;

cht = size.cy;

// the trick is we want a page to be the width/height of the visible area

// so the scroll range would go from [0..image_dimension - control_dimension]

// but judging from the sample code on MSDN, we don't need to do this; the scrollbar will do it for us

// we DO need to handle it when scrolling, though, since the thumb can only go up to this upper limit

// have to do horizontal and vertical separately

ZeroMemory(&si, sizeof (SCROLLINFO));

si.cbSize = sizeof (SCROLLINFO);

si.fMask = SIF_RANGE | SIF_PAGE;

si.nMin = 0;

si.nMax = (int) (areaWidthLONG(data) - 1); // the max point is inclusive, so we have to pass in the last valid value, not the first invalid one (see http://blogs.msdn.com/b/oldnewthing/archive/2003/07/31/54601.aspx); if we don't, we get weird things like the scrollbar sometimes showing one extra scroll position at the end that you can never scroll to

si.nPage = (UINT) cwid;

SetScrollInfo(hwnd, SB_HORZ, &si, TRUE); // redraw the scroll bar

// MSDN sample code does this a second time; let's do it too to be safe

ZeroMemory(&si, sizeof (SCROLLINFO));

si.cbSize = sizeof (SCROLLINFO);

si.fMask = SIF_RANGE | SIF_PAGE;

si.nMin = 0;

si.nMax = (int) (areaHeightLONG(data) - 1);

si.nPage = (UINT) cht;

SetScrollInfo(hwnd, SB_VERT, &si, TRUE);

}

void repaintArea(HWND hwnd, RECT *r)

{

// NULL - the whole area; TRUE - have windows erase if possible

if (InvalidateRect(hwnd, r, TRUE) == 0)

xpanic("error flagging Area as needing repainting after event", GetLastError());

if (UpdateWindow(hwnd) == 0)

xpanic("error repainting Area after event", GetLastError());

}

void areaMouseEvent(HWND hwnd, void *data, DWORD button, BOOL up, uintptr_t heldButtons, LPARAM lParam)

{

int xpos, ypos;

// mouse coordinates are relative to control; make them relative to Area

getScrollPos(hwnd, &xpos, &ypos);

xpos += GET_X_LPARAM(lParam);

ypos += GET_Y_LPARAM(lParam);

finishAreaMouseEvent(data, button, up, heldButtons, xpos, ypos);

}

static LRESULT CALLBACK areaWndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)

{

void *data;

DWORD which;

uintptr_t heldButtons = (uintptr_t) wParam;

LRESULT lResult;

data = getWindowData(hwnd, uMsg, wParam, lParam, &lResult, storeAreaHWND);

if (data == NULL)

return lResult;

switch (uMsg) {

case WM_PAINT:

paintArea(hwnd, data);

return 0;

case WM_ERASEBKGND:

// don't draw a background; we'll do so when painting

// this is to make things flicker-free; see http://msdn.microsoft.com/en-us/library/ms969905.aspx

return 1;

case WM_HSCROLL:

scrollArea(hwnd, data, wParam, SB_HORZ);

return 0;

case WM_VSCROLL:

scrollArea(hwnd, data, wParam, SB_VERT);

return 0;

case WM_SIZE:

adjustAreaScrollbars(hwnd, data);

return 0;

case WM_ACTIVATE:

// don't keep the double-click timer running if the user switched programs in between clicks

areaResetClickCounter(data);

return 0;

case WM_MOUSEMOVE:

areaMouseEvent(hwnd, data, 0, FALSE, heldButtons, lParam);

return 0;

case WM_LBUTTONDOWN:

SetFocus(hwnd);

areaMouseEvent(hwnd, data, 1, FALSE, heldButtons, lParam);

return 0;

case WM_LBUTTONUP:

areaMouseEvent(hwnd, data, 1, TRUE, heldButtons, lParam);

return 0;

case WM_MBUTTONDOWN:

SetFocus(hwnd);

areaMouseEvent(hwnd, data, 2, FALSE, heldButtons, lParam);

return 0;

case WM_MBUTTONUP:

areaMouseEvent(hwnd, data, 2, TRUE, heldButtons, lParam);

return 0;

case WM_RBUTTONDOWN:

SetFocus(hwnd);

areaMouseEvent(hwnd, data, 3, FALSE, heldButtons, lParam);

return 0;

case WM_RBUTTONUP:

areaMouseEvent(hwnd, data, 3, TRUE, heldButtons, lParam);

return 0;

case WM_XBUTTONDOWN:

SetFocus(hwnd);

// values start at 1; we want them to start at 4

which = (DWORD) GET_XBUTTON_WPARAM(wParam) + 3;

heldButtons = (uintptr_t) GET_KEYSTATE_WPARAM(wParam);

areaMouseEvent(hwnd, data, which, FALSE, heldButtons, lParam);

return TRUE; // XBUTTON messages are different!

case WM_XBUTTONUP:

which = (DWORD) GET_XBUTTON_WPARAM(wParam) + 3;

heldButtons = (uintptr_t) GET_KEYSTATE_WPARAM(wParam);

areaMouseEvent(hwnd, data, which, TRUE, heldButtons, lParam);

return TRUE;

case msgAreaKeyDown:

return (LRESULT) areaKeyEvent(data, FALSE, wParam, lParam);

case msgAreaKeyUp:

return (LRESULT) areaKeyEvent(data, TRUE, wParam, lParam);

case msgAreaSizeChanged:

adjustAreaScrollbars(hwnd, data);

repaintArea(hwnd, NULL); // this calls for an update

return 0;

case msgAreaGetScroll:

getScrollPos(hwnd, (int *) wParam, (int *) lParam);

return 0;

case msgAreaRepaint:

repaintArea(hwnd, (RECT *) lParam);

return 0;

case msgAreaRepaintAll:

repaintArea(hwnd, NULL);

return 0;

default:

return DefWindowProcW(hwnd, uMsg, wParam, lParam);

}

xmissedmsg("Area", "areaWndProc()", uMsg);

return 0; // unreached

}

DWORD makeAreaWindowClass(char **errmsg)

{

WNDCLASSW wc;

ZeroMemory(&wc, sizeof (WNDCLASSW));

wc.style = CS_HREDRAW | CS_VREDRAW; // no CS_DBLCLKS because do that manually

wc.lpszClassName = areaWindowClass;

wc.lpfnWndProc = areaWndProc;

wc.hInstance = hInstance;

wc.hIcon = hDefaultIcon;

wc.hCursor = hArrowCursor,

wc.hbrBackground = NULL; // no brush; we handle WM_ERASEBKGND

wc.cbWndExtra = 3 * sizeof (LONG_PTR); // text field handle, text field current x, text field current y

if (RegisterClassW(&wc) == 0) {

*errmsg = "error registering Area window class";

return GetLastError();

}

return 0;

}

HWND newArea(void *data)

{

HWND hwnd;

hwnd = CreateWindowExW(

0,

areaWindowClass, L"",

WS_HSCROLL | WS_VSCROLL | WS_CHILD | WS_VISIBLE | WS_TABSTOP,

CW_USEDEFAULT, CW_USEDEFAULT,

100, 100,

msgwin, NULL, hInstance, data);

if (hwnd == NULL)

xpanic("container creation failed", GetLastError());

return hwnd;

}

static LRESULT CALLBACK areaTextFieldSubProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR id, DWORD_PTR data)

{

switch (uMsg) {

case WM_KILLFOCUS:

ShowWindow(hwnd, SW_HIDE);

areaTextFieldDone((void *) data);

return (*fv_DefSubclassProc)(hwnd, uMsg, wParam, lParam);

case WM_NCDESTROY:

if ((*fv_RemoveWindowSubclass)(hwnd, areaTextFieldSubProc, id) == FALSE)

xpanic("error removing Area TextField subclass (which was for handling WM_KILLFOCUS)", GetLastError());

return (*fv_DefSubclassProc)(hwnd, uMsg, wParam, lParam);

default:

return (*fv_DefSubclassProc)(hwnd, uMsg, wParam, lParam);

}

xmissedmsg("Area TextField", "areaTextFieldSubProc()", uMsg);

return 0; // unreached

}

HWND newAreaTextField(HWND area, void *goarea)

{

HWND tf;

tf = CreateWindowExW(textfieldExtStyle,

L"edit", L"",

textfieldStyle | WS_CHILD,

0, 0, 0, 0,

area, NULL, hInstance, NULL);

if (tf == NULL)

xpanic("error making Area TextField", GetLastError());

if ((*fv_SetWindowSubclass)(tf, areaTextFieldSubProc, 0, (DWORD_PTR) goarea) == FALSE)

xpanic("error subclassing Area TextField to give it its own WM_KILLFOCUS handler", GetLastError());

return tf;

}

void areaOpenTextField(HWND area, HWND textfield, int x, int y, int width, int height)

{

int sx, sy;

int baseX, baseY;

LONG unused;

getScrollPos(area, &sx, &sy);

x += sx;

y += sy;

calculateBaseUnits(textfield, &baseX, &baseY, &unused);

width = MulDiv(width, baseX, 4);

height = MulDiv(height, baseY, 8);

if (MoveWindow(textfield, x, y, width, height, TRUE) == 0)

xpanic("error moving Area TextField in Area.OpenTextFieldAt()", GetLastError());

ShowWindow(textfield, SW_SHOW);

if (SetFocus(textfield) == NULL)

xpanic("error giving Area TextField focus", GetLastError());

}

void areaMarkTextFieldDone(HWND area)

{

SetWindowLongPtrW(area, 0, (LONG_PTR) NULL);

}