✨ Terminal custom color filters

Close #483

Author: GitSquared

src/assets/themes/tron-colorfilter.json

@@ -0,0 +1,34 @@
+{
+    "colors": {
+        "r": 170,
+        "g": 207,
+        "b": 209,
+        "black": "#000000",
+        "light_black": "#05080d",
+        "grey": "#262828"
+    },
+    "cssvars": {
+        "font_main": "United Sans Medium",
+        "font_main_light": "United Sans Light"
+    },
+    "terminal": {
+        "fontFamily": "Fira Mono",
+        "cursorStyle": "block",
+        "foreground": "#aacfd1",
+        "background": "#05080d",
+        "cursor": "#aacfd1",
+        "cursorAccent": "#aacfd1",
+        "selection": "rgba(170,207,209,0.3)",
+        "colorFilter": [
+            "rotate(180)",
+            "saturate(0.5)",
+            "mix(0.7)"
+        ]
+    },
+    "globe": {
+        "base": "#000000",
+        "marker": "#aacfd1",
+        "pin": "#aacfd1",
+        "satellite": "#aacfd1"
+    }
+}

src/classes/terminal.class.js

@@ -27,10 +27,74 @@ class Terminal {
                 this.Ipc.send("terminal_channel-"+this.port, "Resize", cols, rows);
             };
 
+            // Support for custom color filters on the terminal - see #483
+            let doCustomFilter = false;
+
+            // Typechecking condition to ensure that provided filters are valid and prevent code injection
+            if (typeof window.theme.terminal.colorFilter === "object" && window.theme.terminal.colorFilter.length > 0) {
+                doCustomFilter = window.theme.terminal.colorFilter.every((step, i, a) => {
+                    let func = step.slice(0, step.indexOf("("));
+
+                    switch(func) {
+                        case "negate":
+                        case "grayscale":
+                            a[i] = {
+                                func,
+                                arg: []
+                            };
+                            return true;
+                        case "lighten":
+                        case "darken":
+                        case "saturate":
+                        case "desaturate":
+                        case "whiten":
+                        case "blacken":
+                        case "fade":
+                        case "opaquer":
+                        case "rotate":
+                        case "mix":
+                            break;
+                        default:
+                            return false;
+                    }
+
+                    let arg = step.slice(step.indexOf("(")+1, step.indexOf(")"));
+
+                    if (typeof Number(arg) === "number") {
+                        a[i] = {
+                            func,
+                            arg: [Number(arg)]
+                        };
+                        return true;
+                    }
+
+                    return false;
+                });
+            }
+
             let color = require("color");
-            let colorify = (base, target) => {
-                return color(base).grayscale().mix(color(target), 0.3).hex();
-            };
+            let colorify;
+            if (doCustomFilter) {
+                colorify = (base, target) => {
+                    let newColor = color(base);
+                    target = color(target);
+
+                    for (let i = 0; i < window.theme.terminal.colorFilter.length; i++) {
+                        if (window.theme.terminal.colorFilter[i].func === "mix") {
+                            newColor = newColor[window.theme.terminal.colorFilter[i].func](target, ...window.theme.terminal.colorFilter[i].arg);
+                        } else {
+                            newColor = newColor[window.theme.terminal.colorFilter[i].func](...window.theme.terminal.colorFilter[i].arg);
+                        }
+                    }
+
+                    return newColor.hex();
+                };
+            } else {
+                colorify = (base, target) => {
+                    return color(base).grayscale().mix(color(target), 0.3).hex();
+                };
+            }
+
             let themeColor = `rgb(${window.theme.r}, ${window.theme.g}, ${window.theme.b})`;
 
             this.term = new this.xTerm({