Add get_screenshot tool to MCP server and automatic PBM-to-PNG bridge conversion

This commit is contained in:
Adolfo Reyna
2026-05-31 22:52:03 -04:00
parent 444d4c6116
commit f5d153e65f
2 changed files with 67 additions and 0 deletions
+49
View File
@@ -34,6 +34,55 @@ def main():
with urllib.request.urlopen(req, timeout=10.0) as response:
resp_data = response.read().decode("utf-8")
try:
resp_json = json.loads(resp_data)
result = resp_json.get("result", {})
content_list = result.get("content", [])
if len(content_list) > 0 and content_list[0].get("type") == "text":
text_val = content_list[0].get("text", "")
if text_val.startswith("__PBM_BASE64__:"):
b64_pbm = text_val.split(":", 1)[1]
import base64
import subprocess
import os
pbm_bytes = base64.b64decode(b64_pbm)
with open("temp_mcp.pbm", "wb") as pf:
pf.write(pbm_bytes)
# Convert PBM to PNG on macOS using standard sips tool
subprocess.run(["sips", "-s", "format", "png", "temp_mcp.pbm", "--out", "temp_mcp.png"],
stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
if os.path.exists("temp_mcp.png"):
with open("temp_mcp.png", "rb") as pngf:
png_bytes = pngf.read()
b64_png = base64.b64encode(png_bytes).decode("utf-8")
# Replace standard text content with MCP image schema
content_list[0] = {
"type": "image",
"data": b64_png,
"mimeType": "image/png"
}
# Cleanup temp files
try:
os.remove("temp_mcp.pbm")
os.remove("temp_mcp.png")
except:
pass
else:
content_list[0] = {
"type": "text",
"text": "Screenshot captured, but PNG conversion failed on host PC."
}
resp_data = json.dumps(resp_json)
except Exception as ex:
sys.stderr.write(f"Bridge image conversion error: {ex}\n")
sys.stderr.flush()
# Write the response back to stdio for the LLM client
sys.stdout.write(resp_data + "\n")
sys.stdout.flush()
+18
View File
@@ -164,6 +164,11 @@ class MCPServer:
"duration_ms": {"type": "integer", "description": "Scan duration in milliseconds (default 3000)"}
}
}
},
{
"name": "get_screenshot",
"description": "Capture the current reflective LCD screen rendering as a PNG image.",
"inputSchema": {"type": "object", "properties": {}}
}
]
},
@@ -263,5 +268,18 @@ class MCPServer:
devices = self.ble.scan(dur)
return json.dumps(devices)
elif name == "get_screenshot":
import binascii
filename = 'screenshot_mcp.pbm'
try:
self.display.save_screenshot(filename)
with open(filename, 'rb') as f:
data = f.read()
# Encode to base64
b64 = binascii.b2a_base64(data).decode('utf-8').strip()
return f"__PBM_BASE64__:{b64}"
except Exception as e:
raise RuntimeError(f"Screenshot capture failed: {e}")
else:
raise ValueError(f"Unknown tool: {name}")