🔧 Use script to actively search for the image targets [run-ci]

tests/find-target.sh

@@ -0,0 +1,124 @@
+#!/bin/bash
+
+# -------------------------------------------------------------------------------------- #
+# This script searches for a given image on the screen and prints the coordinates of the #
+# upper left corner to STDOUT if it's found. If the image is not found, an exit code     #
+# of 1 is returned.                                                                      #
+#                                                                                        #
+# -s scale_factor: In order to optimize the performance, both, the target image and the  #
+#                  screen capture is scaled down by 1 / scale_factor. Lower numbers can  #
+#                  help finding difficult targets but will also increase the calculation #
+#                  time. Reasonable values are [1...10], default is 4.                   #
+# -f fuzziness:    A mean-squared-error threshold under which a location is considered   #
+#                  to be a match. Default is 0.01. Increase this to make finding a       #
+#                  target more likely but also increase the possibility of false         #
+#                  positives.                                                            #
+# -------------------------------------------------------------------------------------- #
+
+usage() {
+  echo "Usage: $0 -s scale_factor -f fuzziness screen.png target.png" >&2
+}
+
+SCALE_FACTOR=4
+FUZZINESS=0.01
+
+while getopts "s:f:h" opt; do
+  case $opt in
+    s) SCALE_FACTOR="${OPTARG}";;
+    f) FUZZINESS="${OPTARG}";;
+    h) usage; exit 0;;
+    *) usage; exit 1;;
+  esac
+done
+
+shift $((OPTIND-1))
+SCREEN=$1
+TARGET=$2
+
+# Make sure the screen image is given.
+if [[ -z "${SCREEN}" ]]; then
+    usage
+    exit 1
+fi
+
+# Make sure the target image is given.
+if [[ -z "${TARGET}" ]]; then
+    usage
+    exit 1
+fi
+
+# Create a temporary directory.
+WORK_DIR=$(mktemp -d)
+if [[ ! "${WORK_DIR}" || ! -d "${WORK_DIR}" ]]; then
+  echo "Failed to create tmp directory!" >&2
+  exit 1
+fi
+
+# Deletes the temp directory on exit.
+function cleanup {
+  rm -r "${WORK_DIR}"
+}
+
+trap cleanup EXIT
+
+# Reduce the size of the screen capture and the target to optimize the search performance.
+convert ${SCREEN} -resize $((100 / SCALE_FACTOR))% "${WORK_DIR}/screen_small.png"
+convert ${TARGET} -resize $((100 / SCALE_FACTOR))% "${WORK_DIR}/target_small.png"
+
+# Make a search on the reduced images.
+RESULT=$(compare -metric MSE -subimage-search \
+      "${WORK_DIR}/screen_small.png" "${WORK_DIR}/target_small.png" "${WORK_DIR}/out.png" 2>&1)
+
+if [[ $RESULT == *"error"* ]]; then
+  echo "Failed to find the target: ${RESULT}" >&2
+  exit 1
+fi
+
+# We use the position of match to crop the original screen capture tightly around the
+# match. Some padding is added to make sure that the target is contained in the cropped
+# screen capture. We then search one more in the full resolution to get the exact pixel
+# location.
+
+# Here we extract the pixel location of the match in the scaled-down version.
+CROP_X=$(echo "${RESULT}" | awk -F[\,\ ] '{print $4}')
+CROP_Y=$(echo "${RESULT}" | awk -F[\,\ ] '{print $5}')
+
+# We add more padding if the images are more scaled down.
+PADDING=$SCALE_FACTOR
+
+CROP_X=$((CROP_X * SCALE_FACTOR - PADDING))
+CROP_Y=$((CROP_Y * SCALE_FACTOR - PADDING))
+
+# Clamp the result.
+CROP_X=$((CROP_X < 0 ? 0 : CROP_X))
+CROP_Y=$((CROP_Y < 0 ? 0 : CROP_Y))
+
+# The crop size depends on the target image size.
+TARGET_WIDTH=$(identify -format "%[fx:w]" "${TARGET}")
+TARGET_HEIGHT=$(identify -format "%[fx:h]" "${TARGET}")
+CROP_WIDTH=$((TARGET_WIDTH + 2*PADDING))
+CROP_HEIGHT=$((TARGET_HEIGHT + 2*PADDING))
+
+# Perform the crop.
+convert "${SCREEN}" -crop ${CROP_WIDTH}x${CROP_HEIGHT}+${CROP_X}+${CROP_Y} \
+        +repage "${WORK_DIR}/screen_cropped.png"
+
+# Search again on the full resolution.
+RESULT=$(compare -metric MSE -dissimilarity-threshold ${FUZZINESS} -subimage-search \
+      "${WORK_DIR}/screen_cropped.png" "${TARGET}" "${WORK_DIR}/out.png" 2>&1)
+
+if [[ $RESULT == *"error"* ]]; then
+  echo "Failed to find the target: ${RESULT}" >&2
+  exit 1
+fi
+
+# Extract the pixel location from the result. This is now relative to the crop position.
+POS_X=$(echo "${RESULT}" | awk -F[\,\ ] '{print $4}')
+POS_Y=$(echo "${RESULT}" | awk -F[\,\ ] '{print $5}')
+
+# Therefore we have to add the crop position to the result.
+POS_X=$((POS_X + CROP_X))
+POS_Y=$((POS_Y + CROP_Y))
+
+# Finally print our result.
+echo "$POS_X $POS_Y"