feat: Support config in frontmatter.

cSpell.json

@@ -44,6 +44,7 @@
     "faber",
     "flatmap",
     "foswiki",
+    "frontmatter",
     "ftplugin",
     "gantt",
     "gitea",

cypress/integration/rendering/conf-and-directives.spec.js

@@ -14,7 +14,6 @@ describe('Configuration and directives - nodes should be light blue', () => {
         `,
       {}
     );
-    cy.get('svg');
   });
   it('Settings from initialize - nodes should be green', () => {
     imgSnapshotTest(
@@ -28,7 +27,6 @@ graph TD
           end          `,
       { theme: 'forest' }
     );
-    cy.get('svg');
   });
   it('Settings from initialize overriding themeVariable - nodes should be red', () => {
     imgSnapshotTest(
@@ -46,7 +44,6 @@ graph TD
         `,
       { theme: 'base', themeVariables: { primaryColor: '#ff0000' }, logLevel: 0 }
     );
-    cy.get('svg');
   });
   it('Settings from directive - nodes should be grey', () => {
     imgSnapshotTest(
@@ -62,7 +59,24 @@ graph TD
         `,
       {}
     );
-    cy.get('svg');
+  });
+  it('Settings from frontmatter - nodes should be grey', () => {
+    imgSnapshotTest(
+      `
+---
+config:
+  theme: neutral
+---
+graph TD
+          A(Start) --> B[/Another/]
+          A[/Another/] --> C[End]
+          subgraph section
+            B
+            C
+          end
+        `,
+      {}
+    );
   });
 
   it('Settings from directive overriding theme variable - nodes should be red', () => {
@@ -79,7 +93,6 @@ graph TD
         `,
       {}
     );
-    cy.get('svg');
   });
   it('Settings from initialize and directive - nodes should be grey', () => {
     imgSnapshotTest(
@@ -95,7 +108,6 @@ graph TD
         `,
       { theme: 'forest' }
     );
-    cy.get('svg');
   });
   it('Theme from initialize, directive overriding theme variable - nodes should be red', () => {
     imgSnapshotTest(
@@ -111,8 +123,71 @@ graph TD
         `,
       { theme: 'base' }
     );
-    cy.get('svg');
   });
+  it('Theme from initialize, frontmatter overriding theme variable - nodes should be red', () => {
+    imgSnapshotTest(
+      `
+---
+config:
+  theme: base
+  themeVariables:
+    primaryColor: '#ff0000'
+---
+graph TD
+          A(Start) --> B[/Another/]
+          A[/Another/] --> C[End]
+          subgraph section
+            B
+            C
+          end
+        `,
+      { theme: 'forest' }
+    );
+  });
+  it('Theme from initialize, frontmatter overriding theme variable, directive overriding primaryColor - nodes should be red', () => {
+    imgSnapshotTest(
+      `
+---
+config:
+  theme: base
+  themeVariables:
+    primaryColor: '#00ff00'
+---
+%%{init: {'theme': 'base', 'themeVariables':{ 'primaryColor': '#ff0000'}}}%%
+graph TD
+          A(Start) --> B[/Another/]
+          A[/Another/] --> C[End]
+          subgraph section
+            B
+            C
+          end
+        `,
+      { theme: 'forest' }
+    );
+  });
+
+  it('should render if values are not quoted properly', () => {
+    // #ff0000 is not quoted properly, and will evaluate to null.
+    // This test ensures that the rendering still works.
+    imgSnapshotTest(
+      `---
+config:
+  theme: base
+  themeVariables:
+    primaryColor: #ff0000
+---
+graph TD
+          A(Start) --> B[/Another/]
+          A[/Another/] --> C[End]
+          subgraph section
+            B
+            C
+          end
+        `,
+      { theme: 'forest' }
+    );
+  });
+
   it('Theme variable from initialize, theme from directive - nodes should be red', () => {
     imgSnapshotTest(
       `
@@ -127,13 +202,11 @@ graph TD
         `,
       { themeVariables: { primaryColor: '#ff0000' } }
     );
-    cy.get('svg');
   });
   describe('when rendering several diagrams', () => {
     it('diagrams should not taint later diagrams', () => {
       const url = 'http://localhost:9000/theme-directives.html';
       cy.visit(url);
-      cy.get('svg');
       cy.matchImageSnapshot('conf-and-directives.spec-when-rendering-several-diagrams-diagram-1');
     });
   });

demos/er.html

@@ -21,6 +21,8 @@
     <pre class="mermaid">
       ---
       title: This is a title
+      config:
+        theme: forest
       ---
       erDiagram
         %% title This is a title

demos/flowchart.html

@@ -123,6 +123,13 @@ <h3>graph</h3>
 
     <h3>flowchart</h3>
     <pre class="mermaid">
+    ---
+    title: This is another complicated flow
+    config:
+      theme: base
+      flowchart:
+        curve: cardinal
+    ---
     flowchart LR
     sid-B3655226-6C29-4D00-B685-3D5C734DC7E1["
 

docs/config/configuration.md

@@ -10,10 +10,41 @@ When mermaid starts, configuration is extracted to determine a configuration to
 
 - The default configuration
 - Overrides at the site level are set by the initialize call, and will be applied to all diagrams in the site/app. The term for this is the **siteConfig**.
-- Directives - diagram authors can update select configuration parameters directly in the diagram code via directives. These are applied to the render config.
+- Frontmatter (v\<MERMAID_RELEASE_VERSION>+) - diagram authors can update select configuration parameters in the frontmatter of the diagram. These are applied to the render config.
+- Directives (Deprecated by Frontmatter) - diagram authors can update select configuration parameters directly in the diagram code via directives. These are applied to the render config.
 
 **The render config** is configuration that is used when rendering by applying these configurations.
 
+## Frontmatter config
+
+The entire mermaid configuration (except the secure configs) can be overridden by the diagram author in the frontmatter of the diagram. The frontmatter is a YAML block at the top of the diagram.
+
+```mermaid-example
+---
+title: Hello Title
+config:
+  theme: base
+  themeVariables:
+    primaryColor: "#00ff00"
+---
+flowchart
+	Hello --> World
+
+```
+
+```mermaid
+---
+title: Hello Title
+config:
+  theme: base
+  themeVariables:
+    primaryColor: "#00ff00"
+---
+flowchart
+	Hello --> World
+
+```
+
 ## Theme configuration
 
 ## Starting mermaid

docs/config/directives.md

@@ -6,6 +6,9 @@
 
 # Directives
 
+> **Warning**
+> Directives are deprecated from v\<MERMAID_RELEASE_VERSION>. Please use the `config` key in frontmatter to pass configuration. See [Configuration](./configuration.md) for more details.
+
 ## Directives
 
 Directives give a diagram author the capability to alter the appearance of a diagram before rendering by changing the applied configuration.

docs/config/setup/interfaces/mermaidAPI.ParseOptions.md

@@ -16,4 +16,4 @@
 
 #### Defined in
 
-[mermaidAPI.ts:77](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/mermaidAPI.ts#L77)
+[mermaidAPI.ts:78](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/mermaidAPI.ts#L78)

docs/config/setup/interfaces/mermaidAPI.RenderResult.md

@@ -39,7 +39,7 @@ bindFunctions?.(div); // To call bindFunctions only if it's present.
 
 #### Defined in
 
-[mermaidAPI.ts:97](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/mermaidAPI.ts#L97)
+[mermaidAPI.ts:98](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/mermaidAPI.ts#L98)
 
 ---
 
@@ -51,4 +51,4 @@ The svg code for the rendered graph.
 
 #### Defined in
 
-[mermaidAPI.ts:87](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/mermaidAPI.ts#L87)
+[mermaidAPI.ts:88](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/mermaidAPI.ts#L88)

docs/config/setup/modules/config.md

@@ -14,7 +14,7 @@
 
 #### Defined in
 
-[config.ts:7](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L7)
+[config.ts:8](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L8)
 
 ## Functions
 
@@ -26,17 +26,17 @@ Pushes in a directive to the configuration
 
 #### Parameters
 
-| Name        | Type  | Description              |
-| :---------- | :---- | :----------------------- |
-| `directive` | `any` | The directive to push in |
+| Name        | Type            | Description              |
+| :---------- | :-------------- | :----------------------- |
+| `directive` | `MermaidConfig` | The directive to push in |
 
 #### Returns
 
 `void`
 
 #### Defined in
 
-[config.ts:191](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L191)
+[config.ts:188](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L188)
 
 ---
 
@@ -60,7 +60,7 @@ The currentConfig
 
 #### Defined in
 
-[config.ts:137](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L137)
+[config.ts:131](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L131)
 
 ---
 
@@ -118,7 +118,7 @@ The siteConfig
 
 #### Defined in
 
-[config.ts:223](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L223)
+[config.ts:218](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L218)
 
 ---
 
@@ -147,7 +147,7 @@ options in-place
 
 #### Defined in
 
-[config.ts:152](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L152)
+[config.ts:146](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L146)
 
 ---
 
@@ -242,18 +242,18 @@ The new siteConfig
 
 #### Parameters
 
-| Name          | Type            |
-| :------------ | :-------------- |
-| `siteCfg`     | `MermaidConfig` |
-| `_directives` | `any`\[]        |
+| Name          | Type               |
+| :------------ | :----------------- |
+| `siteCfg`     | `MermaidConfig`    |
+| `_directives` | `MermaidConfig`\[] |
 
 #### Returns
 
 `MermaidConfig`
 
 #### Defined in
 
-[config.ts:14](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L14)
+[config.ts:15](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/config.ts#L15)
 
 ---
 

docs/config/setup/modules/defaultConfig.md

@@ -10,7 +10,7 @@
 
 ### configKeys
 
-• `Const` **configKeys**: `string`\[]
+• `Const` **configKeys**: `Set`<`string`>
 
 #### Defined in