feat:change model

spx-backend/SVG_GENERATION_CONFIG.md

@@ -163,6 +163,41 @@ Generates an image and returns metadata information.
 }
 ```
 
+### POST /character/style/change
+Changes character styling while preserving character identity.
+
+**Request Body (multipart/form-data):**
+```
+image: [PNG file]                      # Required: Character image to be restyled
+style_prompt: "change to casual clothes" # Required: Description of style changes
+strength: 0.3                         # Optional: Transformation strength (0-1, default: 0.3)
+style: "realistic_image"               # Optional: Image style
+sub_style: "detailed"                  # Optional: Sub-style
+negative_prompt: "ugly, distorted"     # Optional: What to avoid
+provider: "recraft"                    # Optional: Provider (default: recraft)
+preserve_identity: true                # Optional: Preserve character identity (default: true)
+```
+
+**Response:**
+```json
+{
+  "id": "recraft_style_1234567890",
+  "url": "https://example.com/styled-character.png",
+  "kodo_url": "https://kodo.example.com/styled-character.svg",
+  "ai_resource_id": 12345,
+  "original_prompt": "change to casual clothes",
+  "style_prompt": "保持角色的面部特征、体型和基本外观不变，只改变change to casual clothes，确保角色身份完全保持不变",
+  "negative_prompt": "ugly, distorted, 改变面部特征, 改变角色身份, 不同的人",
+  "style": "realistic_image",
+  "strength": 0.3,
+  "width": 1024,
+  "height": 1024,
+  "provider": "recraft",
+  "preserve_identity": true,
+  "created_at": "2025-01-01T12:00:00Z"
+}
+```
+
 ## Provider Selection
 
 You can specify which provider to use in the request:
@@ -174,7 +209,7 @@ You can specify which provider to use in the request:
 Each provider has different strengths:
 
 - **SVG.IO**: Direct SVG generation, good for simple vector graphics
-- **Recraft**: High-quality AI image generation with vectorization
+- **Recraft**: High-quality AI image generation with vectorization, supports image beautification and character style changes
 - **OpenAI**: LLM-powered SVG code generation, highly customizable
 
 ## Development Setup
@@ -214,4 +249,12 @@ curl -X POST http://localhost:8080/image \
     "model": "recraftv3",
     "size": "1024x1024"
   }'
+
+# Change character style
+curl -X POST http://localhost:8080/character/style/change \
+  -F "[email protected]" \
+  -F "style_prompt=change to medieval knight armor" \
+  -F "strength=0.4" \
+  -F "preserve_identity=true" \
+  -F "provider=recraft"
 ```

spx-backend/cmd/spx-backend/post_character_style_change.yap

@@ -0,0 +1,84 @@
+// Change character styling while preserving character identity.
+//
+// Request:
+//   POST /character/style/change
+
+import (
+	"io"
+	"strconv"
+
+	"github.com/goplus/builder/spx-backend/internal/controller"
+	"github.com/goplus/builder/spx-backend/internal/svggen"
+)
+
+ctx := &Context
+if _, ok := ensureAuthenticatedUser(ctx); !ok {
+	return
+}
+
+// Parse multipart form data
+err := ctx.Request.ParseMultipartForm(10 << 20) // 10MB max memory
+if err != nil {
+	replyWithCodeMsg(ctx, errorInvalidArgs, "Failed to parse multipart form")
+	return
+}
+
+// Get image file from form
+file, _, err := ctx.Request.FormFile("image")
+if err != nil {
+	replyWithCodeMsg(ctx, errorInvalidArgs, "Image file is required")
+	return
+}
+defer file.Close()
+
+// Read image data
+imageData, err := io.ReadAll(file)
+if err != nil {
+	replyWithCodeMsg(ctx, errorInvalidArgs, "Failed to read image data")
+	return
+}
+
+// Parse other form parameters
+params := &controller.ChangeCharacterStyleParams{
+	StylePrompt:      ctx.Request.FormValue("style_prompt"),
+	Strength:         0.3, // Default value for character preservation
+	Style:            ctx.Request.FormValue("style"),
+	SubStyle:         ctx.Request.FormValue("sub_style"),
+	NegativePrompt:   ctx.Request.FormValue("negative_prompt"),
+	Provider:         svggen.ProviderRecraft, // Default to recraft
+	PreserveIdentity: true,                   // Default to preserve identity
+}
+
+// Parse strength if provided
+if strengthStr := ctx.Request.FormValue("strength"); strengthStr != "" {
+	if strength, err := strconv.ParseFloat(strengthStr, 64); err == nil {
+		params.Strength = strength
+	}
+}
+
+// Parse provider if provided
+if providerStr := ctx.Request.FormValue("provider"); providerStr != "" {
+	params.Provider = svggen.Provider(providerStr)
+}
+
+// Parse preserve_identity if provided
+if preserveStr := ctx.Request.FormValue("preserve_identity"); preserveStr != "" {
+	if preserve, err := strconv.ParseBool(preserveStr); err == nil {
+		params.PreserveIdentity = preserve
+	}
+}
+
+// Validate parameters
+if ok, msg := params.Validate(); !ok {
+	replyWithCodeMsg(ctx, errorInvalidArgs, msg)
+	return
+}
+
+// Change character style
+result, err := ctrl.ChangeCharacterStyle(ctx.Context(), params, imageData)
+if err != nil {
+	replyWithInnerError(ctx, err)
+	return
+}
+
+json result

spx-backend/internal/controller/character_style_change_test.go

@@ -0,0 +1,148 @@
+package controller
+
+import (
+	"context"
+	"testing"
+
+	"github.com/goplus/builder/spx-backend/internal/svggen"
+)
+
+func TestController_ChangeCharacterStyle_ValidationErrors(t *testing.T) {
+	ctrl := &Controller{}
+
+	ctx := context.Background()
+
+	tests := []struct {
+		name      string
+		params    *ChangeCharacterStyleParams
+		imageData []byte
+		wantErr   string
+	}{
+		{
+			name: "empty image data",
+			params: &ChangeCharacterStyleParams{
+				StylePrompt:      "change outfit",
+				Strength:         0.5,
+				Provider:         svggen.ProviderRecraft,
+				PreserveIdentity: true,
+			},
+			imageData: []byte{},
+			wantErr:   "image data is required",
+		},
+		{
+			name: "oversized image data",
+			params: &ChangeCharacterStyleParams{
+				StylePrompt:      "change outfit",
+				Strength:         0.5,
+				Provider:         svggen.ProviderRecraft,
+				PreserveIdentity: true,
+			},
+			imageData: make([]byte, 6*1024*1024), // 6MB, exceeds 5MB limit
+			wantErr:   "image size exceeds 5MB limit",
+		},
+		{
+			name: "invalid image format - not PNG",
+			params: &ChangeCharacterStyleParams{
+				StylePrompt:      "change outfit",
+				Strength:         0.5,
+				Provider:         svggen.ProviderRecraft,
+				PreserveIdentity: true,
+			},
+			imageData: []byte{0xFF, 0xD8, 0xFF, 0xE0}, // JPEG signature
+			wantErr:   "only PNG format is supported for character style change",
+		},
+		{
+			name: "valid PNG but params validation fails",
+			params: &ChangeCharacterStyleParams{
+				StylePrompt: "hi", // Too short
+				Strength:    0.5,
+				Provider:    svggen.ProviderRecraft,
+			},
+			imageData: []byte{0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A}, // Valid PNG
+			wantErr:   "style_prompt must be at least 3 characters",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Validate params first if they should fail
+			if tt.wantErr == "style_prompt must be at least 3 characters" {
+				ok, msg := tt.params.Validate()
+				if ok {
+					t.Errorf("Expected params validation to fail")
+					return
+				}
+				if msg != tt.wantErr {
+					t.Errorf("Expected validation error %q, got %q", tt.wantErr, msg)
+				}
+				return
+			}
+
+			_, err := ctrl.ChangeCharacterStyle(ctx, tt.params, tt.imageData)
+			if err == nil {
+				t.Errorf("ChangeCharacterStyle() should return error, got nil")
+				return
+			}
+
+			if err.Error() != tt.wantErr {
+				t.Errorf("ChangeCharacterStyle() error = %q, want %q", err.Error(), tt.wantErr)
+			}
+		})
+	}
+}
+
+// Note: Controller integration tests with full mocking would require dependency injection.
+// The core business logic is already tested through:
+// 1. Parameter validation tests (in svg_test.go)
+// 2. Recraft service tests (in recraft_test.go)
+// 3. Input validation tests (below)
+
+// Test the PNG format validation helper function
+func TestController_isPNGFormat_Additional(t *testing.T) {
+	ctrl := &Controller{}
+
+	tests := []struct {
+		name     string
+		data     []byte
+		wantPNG  bool
+	}{
+		{
+			name:    "valid PNG with extra data",
+			data:    append([]byte{0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A}, make([]byte, 100)...),
+			wantPNG: true,
+		},
+		{
+			name:    "partial PNG signature",
+			data:    []byte{0x89, 0x50, 0x4E, 0x47}, // Only first 4 bytes
+			wantPNG: false,
+		},
+		{
+			name:    "corrupted PNG signature - wrong middle bytes",
+			data:    []byte{0x89, 0x50, 0x4E, 0x48, 0x0D, 0x0A, 0x1A, 0x0A}, // 0x48 instead of 0x47
+			wantPNG: false,
+		},
+		{
+			name:    "GIF signature",
+			data:    []byte{0x47, 0x49, 0x46, 0x38, 0x39, 0x61}, // GIF89a
+			wantPNG: false,
+		},
+		{
+			name:    "BMP signature",
+			data:    []byte{0x42, 0x4D}, // BM
+			wantPNG: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := ctrl.isPNGFormat(tt.data)
+			if got != tt.wantPNG {
+				t.Errorf("isPNGFormat() = %v, want %v", got, tt.wantPNG)
+			}
+		})
+	}
+}
+
+// Note: Tests for Kodo failure, Database failure, and Vector service failure scenarios
+// would be implemented as integration tests with proper dependency injection.
+// These scenarios are critical for production reliability but require more complex test setup.