Basic example
This commit is contained in:
Ingvar Stepanyan
246
api.cpp
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246
api.cpp
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#include <emscripten.h>
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#include <emscripten/bind.h>
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#include <emscripten/val.h>
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#include <gphoto2/gphoto2.h>
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#include <iostream>
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using emscripten::val;
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void gpp_try(int status) {
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if (status != GP_OK) {
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throw std::runtime_error(gp_result_as_string(status));
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}
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}
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void gpp_error(GPContext *context, const char *text, void *data) {
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throw std::runtime_error(text);
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}
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#define GPP_CALL(RET, EXPR) \
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({ \
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RET OUT; \
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RET *_ = &OUT; \
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gpp_try(EXPR); \
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OUT; \
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})
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EM_JS([[noreturn]] void, throw_msg, (const char *msg),
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{ throw new Error(UTF8ToString(msg)); });
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template <typename Func>
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auto gpp_rethrow(Func func) {
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try {
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return func();
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} catch (std::exception &e) {
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throw_msg(e.what());
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}
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}
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const thread_local val Uint8Array = val::global("Uint8Array");
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const thread_local val Blob = val::global("Blob");
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class Context {
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public:
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Context()
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: camera(nullptr, gp_camera_unref),
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context(nullptr, gp_context_unref),
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config(nullptr, gp_widget_unref) {
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gpp_rethrow([=]() {
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camera.reset(GPP_CALL(Camera *, gp_camera_new(_)));
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context.reset(gp_context_new());
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gp_context_set_error_func(context.get(), gpp_error, nullptr);
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gpp_try(gp_camera_init(camera.get(), context.get()));
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});
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}
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Context(int foo): Context() {}
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val configToJS() {
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return gpp_rethrow([=]() {
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if (config.get() == nullptr) {
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config.reset(
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GPP_CALL(CameraWidget *,
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gp_camera_get_config(camera.get(), _, context.get())));
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}
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return walk_config(config.get());
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});
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}
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void setConfigValue(int id, val value) {
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gpp_rethrow([=]() {
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auto widget = GPP_CALL(CameraWidget *,
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gp_widget_get_child_by_id(config.get(), id, _));
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auto type = GPP_CALL(CameraWidgetType, gp_widget_get_type(widget, _));
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switch (type) {
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case GP_WIDGET_RANGE: {
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float number = value.as<float>();
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gpp_try(gp_widget_set_value(widget, &number));
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break;
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}
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case GP_WIDGET_MENU:
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case GP_WIDGET_RADIO:
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case GP_WIDGET_TEXT: {
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auto str = value.as<std::string>();
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gpp_try(gp_widget_set_value(widget, str.c_str()));
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break;
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}
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case GP_WIDGET_TOGGLE: {
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int on = value.as<bool>() ? 1 : 0;
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gpp_try(gp_widget_set_value(widget, &on));
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break;
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}
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default: {
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throw std::logic_error("unimplemented");
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}
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}
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gpp_try(gp_camera_set_config(camera.get(), config.get(), context.get()));
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});
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}
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val capturePreviewAsBlob() {
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return gpp_rethrow([=]() {
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class Output {
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public:
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Output() : totalSize(0), chunks(val::array()) {}
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void push(const uint8_t *data, unsigned long size) {
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chunks.call<void>(
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"push",
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Uint8Array.new_(emscripten::typed_memory_view(size, data)));
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totalSize += size;
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}
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uint64_t getTotalSize() { return totalSize; }
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val getChunks() { return chunks; }
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private:
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uint64_t totalSize;
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val chunks;
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};
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static CameraFileHandler handler = {
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.size =
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[](void *priv, uint64_t *size) {
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*size = static_cast<Output *>(priv)->getTotalSize();
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return GP_OK;
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},
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.read = [](void *priv, unsigned char *data,
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uint64_t *len) { return GP_ERROR_NOT_SUPPORTED; },
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.write =
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[](void *priv, unsigned char *data, uint64_t *len) {
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static_cast<Output *>(priv)->push(data, *len);
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return GP_OK;
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}};
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Output output;
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std::unique_ptr<CameraFile, decltype(&gp_file_unref)> file(
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GPP_CALL(CameraFile *,
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gp_file_new_from_handler(_, &handler, &output)),
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gp_file_unref);
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gpp_try(
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gp_camera_capture_preview(camera.get(), file.get(), context.get()));
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auto mime_type =
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GPP_CALL(const char *, gp_file_get_mime_type(file.get(), _));
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val blob_opts = val::object();
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blob_opts.set("type", mime_type);
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return Blob.new_(output.getChunks(), std::move(blob_opts));
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});
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}
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private:
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std::unique_ptr<Camera, decltype(&gp_camera_unref)> camera;
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std::unique_ptr<GPContext, decltype(&gp_context_unref)> context;
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std::unique_ptr<CameraWidget, decltype(&gp_widget_unref)> config;
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static val walk_config(CameraWidget *widget) {
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val result = val::object();
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result.set("id", GPP_CALL(int, gp_widget_get_id(widget, _)));
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result.set("name", GPP_CALL(const char *, gp_widget_get_name(widget, _)));
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result.set("info", GPP_CALL(const char *, gp_widget_get_info(widget, _)));
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result.set("label", GPP_CALL(const char *, gp_widget_get_label(widget, _)));
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result.set("readonly",
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GPP_CALL(int, gp_widget_get_readonly(widget, _)) != 0);
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auto type = GPP_CALL(CameraWidgetType, gp_widget_get_type(widget, _));
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switch (type) {
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case GP_WIDGET_RANGE: {
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result.set("type", "range");
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result.set("value", GPP_CALL(float, gp_widget_get_value(widget, _)));
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float min, max, step;
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gpp_try(gp_widget_get_range(widget, &min, &max, &step));
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result.set("min", min);
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result.set("max", max);
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result.set("step", step);
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break;
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}
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case GP_WIDGET_MENU:
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case GP_WIDGET_RADIO: {
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result.set("type", type == GP_WIDGET_MENU ? "menu" : "radio");
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result.set("value",
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GPP_CALL(const char *, gp_widget_get_value(widget, _)));
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val choices = val::array();
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for (int i = 0, n = gp_widget_count_choices(widget); i < n; i++) {
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choices.call<void>(
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"push",
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val(GPP_CALL(const char *, gp_widget_get_choice(widget, i, _))));
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}
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result.set("choices", choices);
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break;
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}
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case GP_WIDGET_TOGGLE: {
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result.set("type", "toggle");
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result.set("value", GPP_CALL(int, gp_widget_get_value(widget, _)) != 0);
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break;
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}
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case GP_WIDGET_TEXT: {
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result.set("type", "text");
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result.set("value",
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GPP_CALL(const char *, gp_widget_get_value(widget, _)));
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break;
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}
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case GP_WIDGET_WINDOW:
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case GP_WIDGET_SECTION: {
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result.set("type", type == GP_WIDGET_WINDOW ? "window" : "section");
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val children = val::array();
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for (int i = 0, n = gp_widget_count_children(widget); i < n; i++) {
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auto child =
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GPP_CALL(CameraWidget *, gp_widget_get_child(widget, i, _));
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children.call<void>("push", walk_config(child));
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}
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result.set("children", children);
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break;
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}
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default: {
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throw std::logic_error("unimplemented");
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}
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}
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return result;
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}
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};
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EMSCRIPTEN_BINDINGS(gphoto2_js_api) {
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emscripten::class_<Context>("Context")
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.constructor<>()
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.function("configToJS", &Context::configToJS)
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.function("setConfigValue", &Context::setConfigValue)
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.function("capturePreviewAsBlob", &Context::capturePreviewAsBlob);
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}
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