Render with fbo to texture - phunm211/skia-pack GitHub Wiki

void renderTextToTexture(GLuint textureId, int width, int height) {
    if (!grContext) {
        LOGE("GrContext not initialized.");
        return;
    }

    // 1. Gắn textureId vào FBO
    GLuint fbo;
    glGenFramebuffers(1, &fbo);
    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textureId, 0);

    GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
    if (status != GL_FRAMEBUFFER_COMPLETE) {
        LOGE("Framebuffer is not complete: 0x%x", status);
        glBindFramebuffer(GL_FRAMEBUFFER, 0);
        glDeleteFramebuffers(1, &fbo);
        return;
    }

    // 2. Wrap textureId thành GrBackendTexture
    GrGLTextureInfo texInfo;
    texInfo.fID = textureId;
    texInfo.fTarget = GL_TEXTURE_2D;
    texInfo.fFormat = GL_RGBA8;

    GrBackendTexture backendTexture(width, height, GrMipmapped::kNo, texInfo);

    SkColorType colorType = kRGBA_8888_SkColorType;
    auto surface = SkSurfaces::WrapBackendTexture(
        grContext.get(),
        backendTexture,
        kBottomLeft_GrSurfaceOrigin,
        colorType,
        SkColorSpace::MakeSRGB(),
        nullptr
    );

    if (!surface) {
        LOGE("Failed to create surface from textureId.");
        glBindFramebuffer(GL_FRAMEBUFFER, 0);
        glDeleteFramebuffers(1, &fbo);
        return;
    }

    // 3. Vẽ chữ vào surface này
    SkCanvas* canvas = surface->getCanvas();
    canvas->clear(SK_ColorTRANSPARENT);

    SkPaint paint;
    paint.setColor(SK_ColorBLACK);
    paint.setAntiAlias(true);

    sk_sp<SkFontMgr> fontMgr = SkFontMgr_New_Custom_Directory("/system/fonts");
    sk_sp<SkTypeface> typeface = fontMgr->matchFamilyStyle("Roboto", SkFontStyle());
    SkFont font(typeface, 48);

    canvas->drawString("Hello from Skia to Texture", 50, 100, font, paint);

    grContext->flushAndSubmit();

    // 4. Dọn FBO
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    glDeleteFramebuffers(1, &fbo);

    LOGI("Successfully rendered text to textureId: %u", textureId);
}