Automate UI Modernization with Delphi Form Converter

Step-by-Step Guide: Converting Legacy Delphi Forms with Delphi Form ConverterConverting legacy Delphi forms—especially older VCL (Visual Component Library) forms—into modern frameworks such as FireMonkey (FMX) or updated VCL versions can be time-consuming and error-prone if done entirely by hand. A Delphi Form Converter automates much of the repetitive work, preserves form layouts and properties, and helps modernize an application’s UI faster. This guide walks through the full conversion process: preparation, using the converter, handling common issues, testing, and final cleanup.

Why convert legacy Delphi forms?

• Maintainability: Modern frameworks and updated Delphi versions include bug fixes, improved components, and active support.
• Cross-platform needs: FMX enables building for Windows, macOS, iOS, and Android—VCL is Windows-only.
• Visual refresh: Newer styles, retina support, and layout managers make UI updates easier.
• Performance and compatibility: Removing deprecated components and replacing them with supported ones reduces runtime problems.

Preparation

1. Inventory your project

   • List all forms (.dfm/.fmx), units, third-party components, and runtime dependencies.
   • Note Delphi compiler versions originally used and the target Delphi version.

2. Back up everything

   • Create a version-controlled branch or a complete backup of the source tree and resource files.
   • Ensure you can revert to the original if conversion introduces regressions.

3. Gather tools and documentation

   • Install the target Delphi IDE and any conversion tools (Delphi Form Converter utility or third-party tools).
   • Collect documentation for both source (legacy VCL) and target frameworks (FMX or newer VCL).

4. Identify incompatible or custom components

   • Make a list of third-party or in-house components that may not exist in the target framework.
   • For custom components, locate source code or decide on replacements/mapping.

5. Plan a phased approach

   • Convert forms in logical groups (by feature, module, or smoke-test priority).
   • Start with low-risk forms to validate the process before tackling complex dialogs.

Using the Delphi Form Converter — Typical Workflow

Note: exact UI and options vary by converter tool; adapt these steps to your chosen utility.

1. Run the converter on a sample form

   • Choose a simple form first to verify the general behavior.
   • Point the converter to the .dfm (text or binary) and .pas source unit.

2. Select conversion options

   • Mapping strategy (VCL → FMX or VCL upgrade).
   • Preserve layout vs. adapt to flexible layout managers.
   • How to handle fonts, anchors, alignments, and margins.
   • Automatic creation of wrapper components or manual placeholders for unsupported controls.

3. Inspect generated files

   • The converter typically produces a new form file (.fmx or updated .dfm), a converted unit, and sometimes a mapping report.
   • Check for TODO or FIXME comments the tool leaves where manual work is required.

4. Integrate converted form into project

   • Add new files to the project group and compile.
   • Resolve compiler directives and unit references if the converter adjusted namespaces or units.

Common Conversion Challenges and How to Fix Them

1) Layout and Anchors

• Problem: Absolute positioning doesn’t translate well to FMX’s scaling and layout system.
• Fix: Replace fixed anchors with FMX layout controls (TLayout, TGridPanelLayout, TFlowLayout). Use Align and Margins for responsive design.

2) Fonts and DPI

• Problem: Text sizes and metrics differ between VCL and FMX.
• Fix: Re-evaluate font sizes after conversion; use scalable units and test at multiple DPI settings.

3) Unsupported or Custom Components

• Problem: Third-party VCL controls often have no FMX equivalent.
• Fix:
  • Replace with native FMX controls or find FMX versions of the third-party library.
  • Wrap original behavior by porting component code to FMX where feasible.
  • Use converter placeholders and implement the missing functionality manually.

4) Event handlers and code-behind differences

• Problem: Property names or event signatures change.
• Fix: Search for compiler errors, then adapt event signatures or refactor code to new APIs. Keep the original business logic separated so conversions mostly affect UI layers.

5) Resource references (images, icons)

• Problem: Resource paths and resource file formats can differ.
• Fix: Reimport bitmaps/assets using the IDE resource manager appropriate for the target framework. Consider vector assets where supported.

Testing Strategy

1. Compile frequently

   • After converting each form, compile to catch unit/namespace issues early.

2. Unit and integration tests

   • Run existing test suites to ensure logic is unchanged.
   • Add UI tests where practical (automated tests for critical flows).

3. Visual QA

   • Compare screenshots between original and converted forms to spot layout regressions.
   • Test across different resolutions, DPI settings, and platforms (for FMX).

4. User acceptance

   • Gather feedback from domain users on layout, behavior, and usability.
   • Prioritize fixes that impact workflows most.

Performance and Memory Considerations

• Profile memory usage and rendering performance, especially when moving to FMX which uses GPU acceleration.
• Optimize large forms by lazy-loading heavy controls or using lightweight placeholders.
• Minimize use of nested high-overhead controls; flatten visual trees where sensible.

Post-conversion Cleanup

• Remove obsolete units, resources, and leftover conversion artifacts.
• Update project-level settings (compiler options, platforms, package references).
• Document changes and conversion decisions in your project repository.

Example: Converting a Simple Login Form (VCL → FMX)

1. Backup original files: LoginForm.pas, LoginForm.dfm
2. Run converter → produces LoginForm.pas (converted), LoginForm.fmx
3. Open in target IDE:
   • Replace TPanel with TLayout or TGridPanelLayout
   • Adjust Align/Margins for responsiveness
   • Replace TImage with TImage (FMX) and reimport PNG resources
   • Reconnect OnClick/OnKeyPress events; fix any signature differences
4. Compile and test input focus, keyboard behavior, and DPI scaling.

Checklist Before Releasing Converted Application

• [ ] All forms compile without errors or warnings relevant to conversion.
• [ ] Critical user flows tested and validated.
• [ ] Third-party/custom components accounted for or replaced.
• [ ] UI looks acceptable across target resolutions and platforms.
• [ ] Performance benchmarks meet expectations.
• [ ] Documentation updated and backups retained.

Converting legacy Delphi forms is a mix of automation and manual refinement. A Delphi Form Converter accelerates the mechanical parts—file translation, property mapping, and basic wiring—while human work focuses on UX adjustments, component replacements, and platform-specific behaviors. With careful planning, iterative testing, and a phased rollout, you can modernize your Delphi applications with minimal disruption.