Embarcadero has released the free Firemonkey premium style pack for Delphi 10 Berlin (probably supports C++Builder). The Style Designer itself has also been upgraded in this version. This new Delphi 10 style premium pack has 11 styles with the newest style called Copper Dark. The premium styles support all four platforms (Android, IOS, OSX, and Windows). You can use the same look and feel for your app across all platforms solidifying your unique brand look and feel. The 11 styles are Copper, Copper Dark, Coral Crystal, Coral Dark, Diamond, Emerald Crystal, Emerald Dark, Jet, Radiant, Sterling, and Vapor. Some styles have a semi transparent glass look and are meant to be used on a Form with a background color or image. Drop a new TStyleBook component on your form and then set the TForm.StyleBook property to your TStyleBook component. Double click the TStyleCollection field and then add a new default TStyleCollectionItem. Double click the TStyleCollectionItem.Resource field to load the Style Designer. Add each platform to the Platform drop down in the Style Designer. Select each platform and then Open your premium style of choice for that platform. Save/Apply the style when you close it. Now you should be able to see the new Styles on each Platform preview of the form.
FMXExpress.com has over 700 tips and tricks for building cross platform apps on Android, IOS, OSX, Windows, and Linux with a single codebase and single UI using the FireMonkey framework found in Delphi and C++Builder.
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