am7xxx: round scaled_height and scaled_width

[libam7xxx.git] / src / am7xxx.c

diff --git a/src/am7xxx.c b/src/am7xxx.c
index 48704de..1035e23 100644 (file)
--- a/src/am7xxx.c
+++ b/src/am7xxx.c
@@ -22,6 +22,7 @@
 #include <stdarg.h>
 #include <errno.h>
 #include <libusb.h>
+#include <math.h>
 
 #include "am7xxx.h"
 #include "serialize.h"
@@ -69,7 +70,7 @@ static struct am7xxx_usb_device_descriptor supported_devices[] = {
 };
 
 /* The header size on the wire is known to be always 24 bytes, regardless of
- * the memory configuration enforced by different architechtures or compilers
+ * the memory configuration enforced by different architectures or compilers
  * for struct am7xxx_header
  */
 #define AM7XXX_HEADER_WIRE_SIZE 24
@@ -244,6 +245,7 @@ static void debug_dump_header(am7xxx_context *ctx, struct am7xxx_header *h)
        (void)ctx;
        (void)h;
 }
+
 static void trace_dump_buffer(am7xxx_context *ctx, const char *message,
                              uint8_t *buffer, unsigned int len)
 {
@@ -445,7 +447,7 @@ typedef enum {
  * device with index 'open_device_index' and returns the correspondent
  * am7xxx_device in the 'dev' parameter; the function returns 0 on success,
  * 1 if the device was already open and a negative value on error.
- * 
+ *
  * NOTES:
  * if scan_devices() fails when called with 'op' == SCAN_OP_BUILD_DEVLIST,
  * the caller might want to call am7xxx_shutdown() in order to remove
@@ -690,12 +692,74 @@ int am7xxx_get_device_info(am7xxx_device *dev,
        return 0;
 }
 
+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);
+
+       return 0;
+}
+
 int am7xxx_send_image(am7xxx_device *dev,
                      am7xxx_image_format format,
                      unsigned int width,
                      unsigned int height,
                      uint8_t *image,
-                     unsigned int size)
+                     unsigned int image_size)
 {
        int ret;
        struct am7xxx_header h = {
@@ -709,7 +773,7 @@ int am7xxx_send_image(am7xxx_device *dev,
                                .format     = format,
                                .width      = width,
                                .height     = height,
-                               .image_size = size,
+                               .image_size = image_size,
                        },
                },
        };
@@ -718,12 +782,12 @@ int am7xxx_send_image(am7xxx_device *dev,
        if (ret < 0)
                return ret;
 
-       if (image == NULL || size == 0) {
-               warning(dev->ctx, "Not sending any data, check the 'data' or 'size' parameters\n");
+       if (image == NULL || image_size == 0) {
+               warning(dev->ctx, "Not sending any data, check the 'image' or 'image_size' parameters\n");
                return 0;
        }
 
-       return send_data(dev, image, size);
+       return send_data(dev, image, image_size);
 }
 
 int am7xxx_set_power_mode(am7xxx_device *dev, am7xxx_power_mode mode)