migrate dib from rust to c++

Author: evmar

cli/src/main.rs

@@ -182,7 +182,7 @@ fn main() -> anyhow::Result<ExitCode> {
             machine.dump_state(0);
             1
         }
-        _ => unreachable!(),
+        _ => unreachable!("{status:?}"),
     };
     Ok(ExitCode::from(exit_code as u8))
 }

exe/cpp/build.sh

@@ -12,7 +12,7 @@ link_flags="/subsystem:console ddraw.lib gdi32.lib kernel32.lib user32.lib"
 # https://devblogs.microsoft.com/cppblog/introducing-the-universal-crt/
 link_flags="$link_flags libcmt.lib libvcruntime.lib libucrt.lib"
 
-for src in cmdline.cc ddraw.cc errors.cc gdi.cc metrics.cc thread.cc; do
+for src in cmdline.cc ddraw.cc dib.cc errors.cc gdi.cc metrics.cc thread.cc; do
     echo $src
     clang-cl $clang_flags $cflags $sdk_flags $src /link $link_flags
 done

exe/cpp/dib.cc

@@ -0,0 +1,224 @@
+// Draw some bitmaps in different ways.
+
+#include "util.h"
+#include <windows.h>
+#include <cstdint>
+
+// Upward-pointing arrow, 16x16 monochrome.
+const uint8_t ARROW[16 * 2] = {
+    0b00000000, 0b00000000,
+    0b00000001, 0b10000000,
+    0b00000011, 0b11000000,
+    0b00000111, 0b11100000,
+    0b00001111, 0b11110000,
+    0b00011111, 0b11111000,
+    0b00111111, 0b11111100,
+    0b01111111, 0b11111110,
+    0b00000011, 0b11000000,
+    0b00000011, 0b11000000,
+    0b00000011, 0b11000000,
+    0b00000011, 0b11000000,
+    0b00000011, 0b11000000,
+    0b00000011, 0b11000000,
+    0b00000011, 0b11000000,
+    0b00000000, 0b00000000,
+};
+
+uint32_t* arrow_rgba() {
+    static uint32_t pixels[16 * 16];
+    for (size_t row = 0; row < sizeof(ARROW); ++row) {
+        uint8_t b = ARROW[row];
+        for (int i = 0; i < 8; ++i) {
+            uint8_t bit = (b >> (7 - i)) & 1;
+            uint32_t color = (bit == 0) ? 0xFF000000 : 0xFFFFFFFF;
+            pixels[row * 8 + i] = color;
+        }
+    }
+    return pixels;
+}
+
+struct State {
+    HBITMAP mono;
+    HBITMAP dib;
+    uint32_t* dib_pixels;
+
+    State() {
+        mono = nullptr;
+        dib = nullptr;
+        dib_pixels = nullptr;
+    }
+
+    void init(HDC hdc) {
+        create_mono();
+        create_dib(hdc, dib);
+    }
+
+    void create_mono() {
+        mono = CreateBitmap(16, 16, 1, 1, ARROW);
+    }
+
+    void create_dib(HDC hdc, HBITMAP& dib) {
+        BITMAPINFO info = {
+            .bmiHeader = {
+                .biSize = sizeof(BITMAPINFOHEADER),
+                .biWidth = 16,
+                .biHeight = 16,
+                .biPlanes = 1,
+                .biBitCount = 32,
+                .biCompression = BI_RGB,
+            },
+        };
+
+        dib = CreateDIBSection(hdc, &info, DIB_RGB_COLORS, (void**)&dib_pixels, nullptr, 0);
+        memcpy(dib_pixels, arrow_rgba(), sizeof(uint32_t) * 16 * 16);
+    }
+};
+
+static State state = {};
+
+void paint_SetDIBitsToDevice(HDC hdc, int y, uint32_t* rgba) {
+    struct Cfg {
+        uint32_t startScan;
+        bool invertY;
+    };
+    Cfg cfgs[] = {
+        {0, false},
+        {0, true},
+    };
+
+    for (size_t i = 0; i < sizeof(cfgs) / sizeof(cfgs[0]); ++i) {
+        BITMAPINFOHEADER info = {};
+        info.biSize = sizeof(BITMAPINFOHEADER);
+        info.biWidth = 16;
+        info.biHeight = cfgs[i].invertY ? -16 : 16;
+        info.biPlanes = 1;
+        info.biBitCount = 32;
+        info.biCompression = BI_RGB;
+
+        int x = 32 + static_cast<int>(i) * 32;
+        SetDIBitsToDevice(
+            hdc,
+            x,
+            y,
+            16,
+            16,
+            0,
+            static_cast<int>(cfgs[i].startScan),
+            cfgs[i].startScan,
+            16,
+            rgba,
+            reinterpret_cast<BITMAPINFO*>(&info),
+            DIB_RGB_COLORS
+        );
+    }
+}
+
+void paint_StretchDIBits(HDC hdc, int y, uint32_t* rgba) {
+    BITMAPINFOHEADER info = {};
+    info.biSize = sizeof(BITMAPINFOHEADER);
+    info.biWidth = 16;
+    info.biHeight = 16;
+    info.biPlanes = 1;
+    info.biBitCount = 32;
+    info.biCompression = BI_RGB;
+
+    StretchDIBits(
+        hdc,
+        32,
+        y,
+        32,
+        32,
+        0,
+        0,
+        16,
+        16,
+        rgba,
+        reinterpret_cast<BITMAPINFO*>(&info),
+        DIB_RGB_COLORS,
+        SRCCOPY
+    );
+}
+
+void paint(HDC hdc) {
+    if (!state.mono) {
+        state.init(hdc);
+    }
+
+    HDC hdc_bitmap = CreateCompatibleDC(hdc);
+
+    int row = 1;
+    SelectObject(hdc_bitmap, state.mono);
+    BitBlt(hdc, 32, row * 32, 16, 16, hdc_bitmap, 0, 0, SRCCOPY);
+    row++;
+
+    SelectObject(hdc_bitmap, state.dib);
+    BitBlt(hdc, 32, row * 32, 16, 16, hdc_bitmap, 0, 0, SRCCOPY);
+    row++;
+
+    uint32_t* rgba = arrow_rgba();
+    paint_SetDIBitsToDevice(hdc, row * 32, rgba);
+    row++;
+
+    paint_StretchDIBits(hdc, row * 32, rgba);
+
+    DeleteDC(hdc_bitmap);
+}
+
+LRESULT CALLBACK wndproc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) {
+    switch (msg) {
+        case WM_DESTROY:
+            PostQuitMessage(0);
+            return 0;
+        case WM_LBUTTONDOWN:
+            for (int i = 0; i < 32 * 2; ++i) {
+                state.dib_pixels[i] = 0xFF0000FF;
+            }
+            InvalidateRect(hwnd, nullptr, FALSE);
+            return 0;
+        case WM_PAINT: {
+            PAINTSTRUCT ps;
+            HDC hdc = BeginPaint(hwnd, &ps);
+            paint(hdc);
+            EndPaint(hwnd, &ps);
+            return 0;
+        }
+        default:
+            return DefWindowProc(hwnd, msg, wparam, lparam);
+    }
+}
+
+HWND create_window() {
+    const char* class_name = "dibs";
+    WNDCLASS wc = {
+        .lpfnWndProc = wndproc,
+        .hbrBackground = reinterpret_cast<HBRUSH>(COLOR_WINDOW + 1),
+        .lpszClassName = class_name,
+    };
+    RegisterClass(&wc);
+
+    HWND hwnd = CreateWindowEx(
+        0,
+        class_name,
+        "title",
+        WS_OVERLAPPEDWINDOW,
+        CW_USEDEFAULT,
+        CW_USEDEFAULT,
+        400,
+        300,
+        nullptr,
+        nullptr,
+        nullptr,
+        nullptr
+    );
+    ShowWindow(hwnd, SW_NORMAL);
+    return hwnd;
+}
+
+extern "C" void mainCRTStartup() {
+    HWND hwnd = create_window();
+    MSG msg;
+    while (GetMessage(&msg, nullptr, 0, 0)) {
+        TranslateMessage(&msg);
+        DispatchMessage(&msg);
+    }
+}