Article-22233-Tools-Palette-Part-32-Crosshair-Magnifier/README.md

Article-22233-Tools-Palette-Part-32-Crosshair-Magnifier

This repository is an article-derived reference project based on the original MQL5 article. It does not claim to reproduce the full original source code unless files are explicitly attached.

## Overview

This project references MQL5 article **Part 32** of a Tools Palette series. The article extends a previously built interactive chart sidebar with a dedicated crosshair subsystem that adds:

- reticle tick-mark overlays
- full-chart vertical and horizontal crosshair lines
- dynamic price and time axis labels
- a circular magnifier lens for zoomed candle inspection
- a double-click measurement mode with anchor, diagonal line, bar count, pip distance, and raw price difference

The implementation described in the article is centered around canvas-based rendering and chart event handling.

## Original Article

- **Article ID:** 22233
- **Author:** Allan Munene Mutiiria
- **Publication date:** 2026.05.21
- **Category:** MQL5 GUI / Chart objects
- **URL:** https://www.mql5.com/en/articles/22233

## Repository Purpose

This repository should be treated as a **reference/reconstruction project** for the article’s described architecture and code fragments.

Its purpose is to document and preserve the article’s main implementation ideas for:

- custom chart navigation overlays in MQL5
- layered bitmap-label canvas rendering
- magnifier lens rendering on live chart data
- measurement tooling integrated into a sidebar-driven UI
- event-driven crosshair interaction and cleanup logic

## Key Concepts

- Custom crosshair rendering beyond the default MetaTrader crosshair
- Reticle overlay with configurable offset, tick length, and thickness
- Magnifier lens with configurable diameter, zoom factor, and cursor offset
- Axis label rendering using chart foreground/background colors
- Canvas layer expansion from basic sidebar/flyout rendering to multiple overlay surfaces
- Bresenham line drawing for measure diagonals
- Double-click detection using microsecond timing
- Conversion between chart coordinates and screen coordinates
- Theme-aware redraw behavior
- Automatic hiding of crosshair elements over sidebar and flyout regions

## Algorithm / Architecture Summary

The article describes the following architecture:

1. **New input parameters**
- `ReticleOffset`
- `ReticleTickLen`
- `ReticleThickness`
- `MagDiameter`
- `MagZoom`
- `MagOffset`
- `AxisLabelFontSize`
- `AxisLabelFont`

2. **Primitive extension**
- `CCanvasPrimitives` is extended with `DrawBresenhamLine(...)` for pixel-level diagonal rendering with alpha blending.

3. **Canvas layer expansion**
- `CCanvasLayer` grows from four canvases to fifteen total surfaces.
- Added canvases include reticle, magnifier, crosshair lines, crosshair labels, measure anchor lines, measure labels, and a full-screen diagonal line canvas.
- Helper methods prefill 1-pixel-wide or 1-pixel-tall line canvases using chart foreground colors.

4. **Dedicated manager class**
- A new `CCrosshairManager` class is introduced between sidebar rendering and chart event handling.
- It tracks visibility flags, measurement state, anchor coordinates, double-click timing, and cached magnifier cursor position.

5. **Rendering responsibilities**
- Draw reticle tick marks on a transparent square canvas.
- Show/hide and reposition vertical/horizontal crosshair lines.
- Render and place price/time axis labels.
- Render a circular magnifier lens with:
- candle bodies and wicks
- bid/ask lines
- circular clipping
- anti-aliased lens border
- center guide marks
- current price label

6. **Measurement mode**
- Double-click toggles measurement anchor mode.
- Anchor time/price and pixel coordinates are stored.
- Vertical/horizontal anchor lines and axis labels are shown.
- A diagonal line is drawn from anchor to current cursor.
- A floating chart label shows bars, pips, and absolute price difference.

7. **Top-level integration**
- Cleanup method removes crosshair and measurement state on tool switch.
- Mouse-move handler coordinates all real-time updates when the crosshair tool is active.

## Mentioned or Attached Files

### Explicitly attached files

No attached source files were available in the processed input.

### Files mentioned in the article text

- `Tools Palette Part 4.mq5`

### Classes mentioned in the article

- `CCanvasPrimitives`
- `CCanvasLayer`
- `CCrosshairManager`
- `CToolsSidebar`

### Methods specifically shown or discussed

- `DrawBresenhamLine`
- `CreateAllCanvases`
- `DestroyAllCanvases`
- `DrawCrossVerticalLinePixels`
- `DrawCrossHorizontalLinePixels`
- `DrawMeasureVerticalLinePixels`
- `DrawMeasureHorizontalLinePixels`
- `DrawReticleTickMarks`
- `ShowReticle`
- `HideReticle`
- `UpdateReticlePosition`
- `ShowCrossVertical`
- `HideCrossVertical`
- `UpdateCrossVerticalPosition`
- `ShowCrossHorizontal`
- `HideCrossHorizontal`
- `UpdateCrossHorizontalPosition`
- `ShowCrossPriceLabel`
- `HideCrossPriceLabel`
- `ShowCrossTimeLabel`
- `HideCrossTimeLabel`
- `DrawAndPositionAxisLabel`
- `UpdateCrosshairAxisLabels`
- `ShowMeasureLines`
- `HideMeasureLines`
- `UpdateMeasureVerticalPosition`
- `UpdateMeasureHorizontalPosition`
- `UpdateMeasureAnchorLabels`
- `ShowMagnifier`
- `HideMagnifier`
- `UpdateMagnifierPosition`
- `DrawMagnifierLensContent`
- `UpdateMeasureDiagonalLine`
- `UpdateMeasurementInfoLabel`
- `HideAllCrosshairElements`
- `ShowAllCrosshairElements`
- `HandleCrosshairDoubleClick`
- `DeleteAllMeasureObjects`
- `CleanupCrosshairOnToolSwitch`
- `HandleCrosshairMouseMove`

## Statistics

- **Inputs added:** 8
- **New canvas layers added:** 11
- **Total canvases after expansion:** 15
- **New manager class introduced:** 1
- **Protected member variables in `CCrosshairManager` described by the article:** 20
- **Protected methods in `CCrosshairManager` declared in the article:** 30

## Tags

`mql5` `metatrader-5` `canvas` `crosshair` `magnifier` `chart-ui` `sidebar` `measurement-tool` `bresenham-line` `interactive-tools`

## Difficulty

Intermediate to Advanced

## Limitations

- The full original project source code is **not available** in the provided input.
- Only article text and embedded code excerpts were provided, so this repository should not be presented as a complete drop-in reproduction.
- The article depends on earlier parts of the Tools Palette series, especially prior sidebar, renderer, event-routing, and tool-registry infrastructure.
- Some referenced base classes and existing methods are not fully included in the provided material.
- Backtesting visuals are described, but no packaged test assets or complete runnable project structure were attached in the processed input.


## Reference

Original article: [Tools Palette Part 32](https://www.mql5.com/en/articles/22233) by Allan Munene Mutiiria.