feat: add winapi example

Author: x1unix

.gitignore

@@ -1,2 +1,3 @@
 .vscode
 .idea
+.DS_Store

README.md

@@ -27,7 +27,7 @@ docker pull x1unix/go-mingw:latest # or "1.21" for specific Go version
 ```
 
 > [!TIP]
-> Please take a look at [full project build example](example/sqlite-app) before starting to work.
+> Please take a look at [examples](example/) before starting to work.
 
 ### Building Go applications inside container
 
@@ -62,7 +62,7 @@ docker run --rm -it -e GOARCH=386 -v /YourPackageSrc:/go/work \
 ```
 
 > [!TIP]
-> See full project build example [here](example/sqlite-app).
+> See check project build examples [here](example).
 
 ### Go linker flags override
 
@@ -144,4 +144,3 @@ make image GO_VERSION=1.20
 
 > [!IMPORTANT]
 > Replace `1.20` with desired Go version.
-

example/README.md

@@ -0,0 +1,6 @@
+# Examples
+
+This directory contains various examples of Go projects with CGO and cross-compilation scripts that use this Docker image.
+
+* [hello](hello) - Simple app that uses CGO with WinAPI.
+* [sqlite-app](sqlite-app) - Example that uses CGO for SQLite driver.

example/hello/.gitignore

@@ -0,0 +1,4 @@
+.vscode
+.idea
+*.exe
+*.db

example/hello/Makefile

@@ -0,0 +1,31 @@
+GO_VERSION := 1.21 # or "latest" for bleeding-edge Go version
+GO_BUILD_FLAGS := -x
+GOCACHE ?= $(shell go env GOCACHE)
+GOPATH ?= $(shell go env GOPATH)
+
+define docker_build
+@echo ":: Building for $(1) in MinGW container..."
+docker run --rm -it \
+	-e GOCACHE=/go/.cache \
+	-e GOARCH=$(1) \
+	-v "$(GOCACHE)":/go/.cache \
+	-v "$(GOPATH)/src":/go/src \
+	-v "$(GOPATH)/pkg":/go/pkg \
+	-v "$(PWD)":/go/work \
+	-w /go/work \
+	x1unix/go-mingw:$(GO_VERSION) \
+	go build $(GO_BUILD_FLAGS) -o hello-$(1).exe .
+endef
+
+.PHONY:all
+all: build-amd64 build-i386 build-arm64
+
+.PHONY: build-amd64 build-i386 build-arm64
+build-amd64:
+	$(call docker_build,amd64)
+
+build-i386:
+	$(call docker_build,386)
+
+build-arm64:
+	$(call docker_build,arm64)

example/hello/README.md

@@ -0,0 +1,7 @@
+# CGO Hello World
+
+![demo](demo.png)
+
+This is a simple app with CGO and invokes `MessageBox` function from WinAPI.
+
+Run `make` to cross-compile program.

example/hello/demo.png

@@ -0,0 +1,3 @@
+module hello
+
+go 1.21

example/hello/go.mod

@@ -0,0 +1,47 @@
+package main
+
+/*
+#cgo LDFLAGS: -lkernel32
+#include <windows.h>
+#include <stdio.h>
+
+// Function to show a MessageBox using WinAPI
+void hello() {
+	SYSTEM_INFO si;
+	ZeroMemory(&si, sizeof(SYSTEM_INFO));
+    GetSystemInfo(&si);
+	char* arch;
+    switch (si.wProcessorArchitecture) {
+        case PROCESSOR_ARCHITECTURE_AMD64:
+            arch = "AMD64";
+            break;
+        case PROCESSOR_ARCHITECTURE_INTEL:
+            arch = "x86";
+            break;
+        case PROCESSOR_ARCHITECTURE_ARM:
+            arch = "ARM";
+            break;
+        case PROCESSOR_ARCHITECTURE_ARM64:
+            arch = "ARM64";
+            break;
+		case PROCESSOR_ARCHITECTURE_IA64:
+			arch = "IA";
+			break;
+        default:
+            arch = "Unknown";
+            break;
+    }
+
+	char message[30];
+	sprintf(message, "Hello from CGO on %s", arch);
+
+	MessageBox(NULL, message, "Hello World", MB_OK);
+}
+*/
+import "C"
+import "fmt"
+
+func main() {
+	fmt.Println("Calling C function to open a MessageBox...")
+	C.hello()
+}

example/hello/main.go

@@ -1,12 +1,11 @@
-GO_VERSION := 1.17 # or "latest" for bleeding-edge Go version
+GO_VERSION := 1.21 # or "latest" for bleeding-edge Go version
 GO_BUILD_FLAGS := -x
 GOCACHE ?= $(shell go env GOCACHE)
 GOPATH ?= $(shell go env GOPATH)
 
 define docker_build
 @echo ":: Building for $(1) in MinGW container..."
 docker run --rm -it \
-	-u "$${UID}:$${GID}" \
 	-e GOCACHE=/go/.cache \
 	-e GOARCH=$(1) \
 	-v "$(GOCACHE)":/go/.cache \