Basic Chart Loading & Display

The most basic ENC Kernel SDK usage flow - load one S-57 cell and display it inside a Win32 or Qt OpenGL widget.

Prerequisites

• henc.h include and henc.lib linking
• A valid OpenGL context (Win32 wglCreateContext or Qt QOpenGLWidget)
• data/encoptions.ini and the S-52 data directory present at runtime
• One S-57 cell (e.g. S57/KR4A4061.000)

Code

#include "henc.h"
#include <stdio.h>

// Assumes a Win32 + OpenGL context has already been prepared by the host app.
int main(int argc, char** argv) {
    // 1. Library init - loads S-52 data + user settings
    if (hencInit() != 0) {
        fprintf(stderr, "hencInit failed - check encoptions.ini and S-52 data path\n");
        return -1;
    }

    // 2. Create a view handle (call hencCreate again per additional view)
    int view = hencCreate();
    if (view < 0) {
        hencDeinit();
        return -2;
    }

    // 3. Bind the current OpenGL context to this view
    hencSelect(view);

    // 4. Viewport - call again from OnSize when the window resizes
    hencSetViewport(view, 0, 0, 1024, 768);

    // 5. Load an S-57 cell (auto-converts to SENC when absent)
    if (hencLoad("S57/KR4A4061.000") != 0) {
        fprintf(stderr, "chart load failed\n");
        hencDelete(view);
        hencDeinit();
        return -3;
    }

    // 6. Initial center + zoom - units are decimal degrees
    hencSetCenter(view, 129.42, 35.10);   // off Busan
    hencSetZoom(view, 12.0);

    // 7. Render - into the back buffer
    hencClearBackground(view);
    hencRender(view);
    hencSwapBuffer(view);                  // double-buffer swap

    // ... your message loop (mouse / keyboard input, re-render as needed) ...

    // 8. Shutdown
    hencDelete(view);                      // release the view handle
    hencDeinit();                          // library + memory teardown
    return 0;
}

Flow at a glance

1. hencInit - once, at app startup
2. hencCreate - once per view (multi-view: repeat)
3. hencSelect - bind to the current GL context
4. hencSetViewport - sync with window size
5. hencLoad - cell or catalog
6. hencSetCenter / hencSetZoom - initial position
7. hencRender + hencSwapBuffer - every frame
8. hencDelete / hencDeinit - at shutdown

Common pitfalls

• hencInit fails: data/encoptions.ini is resolved relative to the working directory. If your launch path differs, use an absolute path.
• Blank screen: hencSelect was not called, or the OpenGL context is not current on the active thread. Call wglMakeCurrent before hencSelect.
• Cell loads but nothing draws: zoom may be outside the cell’s min/max scale band. Try hencSetViewMapByScale or hencSetUseScaleMinMax to debug.