Apply Adjustment

Instructions

Implementation Reference

• src/bridge/script-builder.ts:551-594 (handler)

  The core handler function that builds the Photopea JavaScript script for applying adjustments. Supports brightness/contrast, hue/saturation/lightness, levels, and curves adjustments based on params type and settings.

  export function buildApplyAdjustment(params: ApplyAdjustmentParams): string {
    const { type, settings = {} } = params;
    const lines: string[] = [];
    const layer = `app.activeDocument.activeLayer`;
  
    switch (type) {
      case "brightness": {
        const brightness = (settings.brightness as number) ?? 0;
        const contrast = (settings.contrast as number) ?? 0;
        lines.push(`${layer}.adjustBrightnessContrast(${brightness}, ${contrast});`);
        break;
      }
      case "hue_sat": {
        const hue = (settings.hue as number) ?? 0;
        const saturation = (settings.saturation as number) ?? 0;
        const lightness = (settings.lightness as number) ?? 0;
        lines.push(`${layer}.adjustColorBalance(${hue}, ${saturation}, ${lightness});`);
        break;
      }
      case "levels": {
        const inputMin = (settings.inputMin as number) ?? 0;
        const inputMax = (settings.inputMax as number) ?? 255;
        const gamma = (settings.gamma as number) ?? 1;
        const outputMin = (settings.outputMin as number) ?? 0;
        const outputMax = (settings.outputMax as number) ?? 255;
        lines.push(
          `${layer}.adjustLevels(${inputMin}, ${inputMax}, ${gamma}, ${outputMin}, ${outputMax});`
        );
        break;
      }
      case "curves": {
        const curvePoints = typeof settings.points === "string" && /^[\[\]0-9,.\s-]+$/.test(settings.points)
          ? settings.points
          : "[[0,0],[255,255]]";
        lines.push(`${layer}.adjustCurves(${curvePoints});`);
        break;
      }
      default:
        lines.push(`// Unknown adjustment type: ${type}`);
    }
  
    lines.push(`app.echoToOE('ok');`);
    return lines.join("\n");
  }

• src/tools/image.ts:96-111 (registration)

  Registration of the 'photopea_apply_adjustment' MCP tool with its input schema (type enum + optional settings record), annotations, and the async handler that calls buildApplyAdjustment and executes via bridge.

  // 20. photopea_apply_adjustment
  server.registerTool("photopea_apply_adjustment", {
    title: "Apply Adjustment",
    description: "Apply a destructive image adjustment to the active layer's pixel data. Use select_layer to target a specific layer first. Modifies pixels directly — use undo to revert if needed.",
    inputSchema: {
      type: z.enum(["brightness", "hue_sat", "levels", "curves"]).describe("Adjustment type: 'brightness' for brightness/contrast, 'hue_sat' for hue/saturation/lightness, 'levels' for input levels, 'curves' for tone curves"),
      settings: z.record(z.union([z.number(), z.string(), z.boolean()])).optional().describe("Key-value settings for the adjustment. For brightness: { brightness: -100..100, contrast: -100..100 }. For hue_sat: { hue: -180..180, saturation: -100..100, lightness: -100..100 }. For levels: { inputBlack: 0..255, inputWhite: 0..255 }"),
    },
    annotations: { readOnlyHint: false, destructiveHint: false, idempotentHint: false, openWorldHint: false },
  }, async (params) => {
    const script = buildApplyAdjustment(params);
    bridge.sendActivity({ type: "activity", id: "", tool: "apply_adjustment", summary: `Apply ${params.type} adjustment` });
    const result = await bridge.executeScript(script);
    if (!result.success) return { isError: true, content: [{ type: "text" as const, text: result.error || "Failed to apply adjustment" }] };
    return { content: [{ type: "text" as const, text: `Adjustment applied: ${params.type}` }] };
  });

• src/bridge/types.ts:195-198 (schema)

  TypeScript interface defining the ApplyAdjustmentParams: type (string) and optional settings record for adjustment parameters.

  export interface ApplyAdjustmentParams {
    type: string;
    settings?: Record<string, number | string | boolean>;
  }