+ if (h.packet_type != AM7XXX_PACKET_TYPE_DEVINFO) {
+ error(dev->ctx, "expected packet type: %d, got %d instead!\n",
+ AM7XXX_PACKET_TYPE_DEVINFO, h.packet_type);
+ errno = ENOTSUP;
+ return -ENOTSUP;
+ }
+
+ dev->device_info = malloc(sizeof(*dev->device_info));
+ if (dev->device_info == NULL) {
+ error(dev->ctx, "cannot allocate a device info (%s)\n",
+ strerror(errno));
+ return -ENOMEM;
+ }
+ memset(dev->device_info, 0, sizeof(*dev->device_info));
+
+ dev->device_info->native_width = h.header_data.devinfo.native_width;
+ dev->device_info->native_height = h.header_data.devinfo.native_height;
+#if 0
+ /* No reason to expose these in the public API until we know what they mean */
+ dev->device_info->unknown0 = h.header_data.devinfo.unknown0;
+ dev->device_info->unknown1 = h.header_data.devinfo.unknown1;
+#endif
+
+ return 0;
+}
+
+AM7XXX_PUBLIC int am7xxx_calc_scaled_image_dimensions(am7xxx_device *dev,
+ unsigned int upscale,
+ unsigned int original_width,
+ unsigned int original_height,
+ unsigned int *scaled_width,
+ unsigned int *scaled_height)
+{
+
+ am7xxx_device_info device_info;
+ float width_ratio;
+ float height_ratio;
+ int ret;
+
+ ret = am7xxx_get_device_info(dev, &device_info);
+ if (ret < 0) {
+ error(dev->ctx, "cannot get device info\n");
+ return ret;
+ }
+
+ /*
+ * Check if we need to rescale; if the input image fits the native
+ * dimensions there is no need to, unless we want to upscale.
+ */
+ if (!upscale &&
+ original_width <= device_info.native_width &&
+ original_height <= device_info.native_height ) {
+ debug(dev->ctx, "CASE 0, no rescaling, the original image fits already\n");
+ *scaled_width = original_width;
+ *scaled_height = original_height;
+ return 0;
+ }
+
+ /* Input dimensions relative to the device native dimensions */
+ width_ratio = (float)original_width / device_info.native_width;
+ height_ratio = (float)original_height / device_info.native_height;
+
+ if (width_ratio > height_ratio) {
+ /*
+ * The input is proportionally "wider" than the device viewport
+ * so its height needs to be adjusted
+ */
+ debug(dev->ctx, "CASE 1, original image wider, adjust the scaled height\n");
+ *scaled_width = device_info.native_width;
+ *scaled_height = (unsigned int)lroundf(original_height / width_ratio);
+ } else if (width_ratio < height_ratio) {
+ /*
+ * The input is proportionally "taller" than the device viewport
+ * so its width needs to be adjusted
+ */
+ debug(dev->ctx, "CASE 2 original image taller, adjust the scaled width\n");
+ *scaled_width = (unsigned int)lroundf(original_width / height_ratio);
+ *scaled_height = device_info.native_height;
+ } else {
+ debug(dev->ctx, "CASE 3, just rescale, same aspect ratio already\n");
+ *scaled_width = device_info.native_width;
+ *scaled_height = device_info.native_height;
+ }
+ debug(dev->ctx, "scaled dimensions: %dx%d\n", *scaled_width, *scaled_height);